First let me apologize ahead of time if this is veering off topic.
 
“However scales are pretty lame and useless without chords propping them up whereas chords can stand on their own in a composition.” --- I am going to have to respectively disagree with this statement.
 
 
Historically scales (modes) occurred long before chords (harmony) ever arrived on the scene. A tremendous amount of music was (and still is) written using only scales (Gregorian chant and much “folk/ethnic” music).
 
If we say that modern western music is made up of three basic elements; Rhythm, Melody and Harmony. Then Rhythm is the most important of the three, as all of what we would normally call music has rhythm (example: Varèse - Ionisation). (Gregorian chant does not have a discernible “beat”, but it does have rhythm).
 
Melody is the second most important basic element of music. Melody combined with rhythm accounts for a tremendous amount of music, both historically in the “west” and in the music of many “non-western” traditions.
 
Chords, and by chords I am referring to vertical structures based on the interval of a third, and functional harmony are the third basic element of much of our (western) music and its influence is being felt in more and more of the world and is being embraced or incorporated in the music of non-western traditions, but is still the least of the three basic elements as it is not a required element.   

Agree that both are highly necessary. Scales are especially important if you're to be playing leads (or supporting leads). I also think it helps to have a period on bass (especially in rock / jazz group settings).  This can tie together an understanding of structure alongside the rhythm. It's quite an eye opener for many guitarists who think playing bass is just a one-note trailer.

Beepster
However scales are pretty lame and useless without chords propping them up whereas chords can stand on their own in a composition.

A solo instrumentalist (violin, sax, clarinet, french horn, vocalist, etc... etc...) will imply the progression with their choices of notes (the same can apply to a guitar, piano, bass, etc...). The combination of melody & fills (leading notes) can lead you through a journey far more interesting than a basic chord progression might.
 
Enter Joe Pass (and others) well known for their chord melody's. As already stated chords are just harmonies. When a person can do this it is because they know the relationships and how they all go together. They are masters of chord substitution and may not even play the same chords the next time they play the song. They don't just learn 10 chords and piece up a song/melody, they build those chords from their knowledge of the scales.
 
All that said - try playing the beginning of "You Shook Me All Night Long" without grinding out big open G-C-D chords.... Chords can be fun .... and yes, they are important as well.
 
Just my 2 cents....

"Check out Guitar George, he knows all chords". I agree they go hand-in-hand with each other. To be fluent with all chords and all scales would be incredible as the options are endless. In reality a solid knowledge of the 7 most common scales (modes) and chord theory along with the ability to play and use them in context is huge.
 
Rocky

In my opinion, it depends who you are and how you use/experiment with what you DO know instead of what you do not.
 
For me, everything happened backwards. I didn't know any scales or theory for years. BUT....because I could play chords, I had no problems writing music and had 10 songs under my belt by the time I was 12 years old. Were they good songs? Not really, but they were songs....and without chords, single notes and scales would not have allowed me to write them. Both are important but to me, chords are more important TO ME.
 
Some writers are not scale oriented at all. They lay down chords and create music. Others use scales....what's important depends on the individual. That said, now that I have learned more theory as I grew as a musician and became more of a guitarist capable of soloing, scales and theory became more important. Be that as it may, I still have yet to write a song that is more scalular than chord voiced....and I've written quite a few guitar instrumentals in my time. Yes, the scales give me melody....but the chords are the structure of the song that allow the song to actually be a song for me.
 
So if you can think like a soloist and can write songs based on scales or melodies, that's what you need to focus on. If you are more of a chords player that can write using chords, you use them. If you can combine both, you do so. Whatever method allows you to write and complete a song is the one you should go with. To this day, though I know just a bit more than basic theory, the theory aspect is not what allowed or helped me to write the hundreds of songs I've written and collaborated on. My ear and creativity has gotten me further than anything. That doesn't make it right....it just makes it right for ME or for an individual that may be in the same position as me. :)
 
-Danny

Depends what mood you are in and whether you are wearing leather trousers (pants) or not.

Danny Danzi
In my opinion, it depends who you are and how you use/experiment with what you DO know instead of what you do not.
 
For me, everything happened backwards. I didn't know any scales or theory for years. BUT....because I could play chords, I had no problems writing music and had 10 songs under my belt by the time I was 12 years old. Were they good songs? Not really, but they were songs....and without chords, single notes and scales would not have allowed me to write them. Both are important but to me, chords are more important TO ME.
 
Some writers are not scale oriented at all. They lay down chords and create music. Others use scales....what's important depends on the individual. That said, now that I have learned more theory as I grew as a musician and became more of a guitarist capable of soloing, scales and theory became more important. Be that as it may, I still have yet to write a song that is more scalular than chord voiced....and I've written quite a few guitar instrumentals in my time. Yes, the scales give me melody....but the chords are the structure of the song that allow the song to actually be a song for me.
 
So if you can think like a soloist and can write songs based on scales or melodies, that's what you need to focus on. If you are more of a chords player that can write using chords, you use them. If you can combine both, you do so. Whatever method allows you to write and complete a song is the one you should go with. To this day, though I know just a bit more than basic theory, the theory aspect is not what allowed or helped me to write the hundreds of songs I've written and collaborated on. My ear and creativity has gotten me further than anything. That doesn't make it right....it just makes it right for ME or for an individual that may be in the same position as me. :)
 
-Danny

This right here.  I still primarily write songs from chords.  I can sing out a melody, which tend to end up being scales.  Both are useful, but I start with chords.

I taught myself and learned to play by ear. I still don't know the names of most scales I use. I always recommend people go learn the proper way and I do believe it's best, but I have no regrets. I have a strange thing going that works for me. When I was a kid (and still now) I would imagine a melody in my head and then grab a guitar and figure it out. So I guess I would vote for chords.

I think the most important thing I can tell anybody is to
 
"Learn to recycle everything you already know to play and build up your foundation up from there " .
 
Now what do I mean by that ? 
 
Take something you already know how to play and play it different keys and octaves …
Do this with a song or something you happen to enjoy playing …
On guitar if you know how to play it in A Minor comfortably learn how to play it in Bb Minor just as comfortably ….
Try the keys you are not comfortable with when you are fresh …I promise you if you do that you will lean something new every time you try it …
Then have a go at  running  the chord changes through the cycle of 5 th's ….
After you do the changes in a few keys through the cycle of 5 th's , try playing the changes chromatically or in intervals …
you can do this w tunes you know and chord changes you already know how to play .
Try playing the tune once through and then modulate it up in whole steps , then modulate the tune to  Minor third  to 4 th to  Flat 5 , 6 th , b7 , and Major 7 th …..
 
Keep it simple , 
Take a riff you play in Minor and Play it in major , then Play it as a 7th chord ….
 
Learn triads , then learn triads in all inversions and octaves of the key you are working on ….
George Van Eps wrote a number of books based on triads that were thicker than a local phone book …
I know this because I had them 
Once you have that down w the triads , learn how to stack triads ….
Most complex harmonic content in Pop and Jazz  can be traced back to stacked triads 
Some of the hippest sounding chords in contemporary music are nothing more than two triads stacked on top of each other …
 
Have you ever wondered how a singer can bring down the house by holding one note ? 
Do the same thing on your instrument ….
Find the common tones in the chords of the tune and hold them as you play through the song .Once you have that under your fingers find the one note that is the most common or has the most emotional impact and play that throughout the tune by holding that note in the melody while playing the chords below it ….
 
If you happen to find your self in a room with a musician who happens talk like Einstein was his long lost Daddy leave the room as fast as you can …trust me man the cat can talk a good game but he probably can't play his way out of a paper shopping bag …
 
You are much better off leaning how to do your own work ….your own way w out all the gibber jabber …
 
Scales are important , but if you are gonna learn how to play scales learn how to make music with them …
For the guitar player that is blinded by his own ability on the fret  board ,  do yourself a favor and ask your self this question …
When was the last time your local record shop sold a record that went Gold of a dude shredding away on a C scale ? 
 
Playing scales is just part of paying dues bro ….it is a means to and end… nothing more , nothing less….
 
A big reason why scales are important is because scales contain the harmonic content of the key the scale is in ..
Sure learning to play the scale as individual notes is a good thing to do , but do not stop there … 
Learn to recognize the intervals of the scale … Play the scale in thirds , in fourths , in fifths …ect ect 
Play the scale as two notes at a time with a harmonized third above , then bump the third up an octave and play the scale in Tenths ….
Do that again with the 6 th .put the 7 th on top or the 9 th ….
Be creative and come up with a new thing that is yours …..
 
If your fingers are Jones'ing to run the fretboard , put them Mo Fo's through Boot Camp…
Play your scales in all 12 keys using the 5 finger positions on the guitar for each key of the scale
When you get done with that Play all 12 keys of the scales of each Key in one position ..if you need to slide your first finger down a fret slide it down , if you need to slide your fourth finger up a fret slide it up ….
If you still happen to be Jones'ing  work your way up the whole fret board one fret at a time doing all 12 keys for each fretboard position ….
 
Understand that everything you could ever want to play on the guitar is hidden right there under your nose in plain sight  
Just because you may not have found it or it may even  be possible that you have not chosen to look for it ..
doesn't mean it's not there 
 
Trust me man It's there …right there under your nose hidden in plain sight the whole freaking time 
 
Anyway I got to book for now ….
 
have fun ,
 
Kenny 

To me a knowledge of intervals and their flavor has always been more important than learning chords or scales. Sometimes I don't even think in terms of scales, I'm just playing interval tones that give whatever flavor I'm trying to express at the time. I mean when the chord is a minor 7, you could be playing the major 6 interval or the augmented 5th, both evoke a particular mood. Of course which one you play is influenced by the other chords in the progression - if you're playing over Am7/D7 with an Am tonality then the "correct" 6th would be the major 6 (F#), but who's to say you couldn't play the F natural over the Am7? Similarly, when I'm playing the blues I switch between a major and minor feel quite freely. If you know all of your intervals then it's much easier to learn scales in terms of their interval composition, and you can mix scales freely on the fly without ever having to memorize all the notes in each key.