OK, I lied. It wasn't an album it was this:

That's a hard one - really.
 
My options would be
 
A Hard Days night
In the court of the Crimson King
In Rock
Tubular Bells
A Passion Play
Ziggy Stardust or Stationtostation
Disraeli Gears
Nantucket Sleighride
and a few others...
 
I can't pick just one, so my diplomatic choice would
be the single All my loving. That was the first ever record of my own, and the start of this all.
 

bapu
Where's Pedro?
 
I need some bathroom reading material.
 

Right here!
 
Not in the bathroom, however!
 
For me, it was The Doors, starting with Light My Fire ... and I knew this was better than the Beatles for me, and it meant a lot more.
 
After that ... Janis Joplin and the Holding Company ... Cheap Thrills ... still one of the best albums EVER.
 
Others on my top stuff very early, would have been The Jimi Hendrix Experience ... and what an experience that was ... and the first Crosby, Still, Nash and Young.
 
Creedence Clearwater Revival, the first album.
 
All of these were valuable albums to my formation. 
 
Led Zeppelin 1 and 2 fit in there some.
 
Later, after I moved to California, Amon Duul 2 (Yeti and Dance of the Lemmings) and Tangerine Dream (Atem and Phaedra).
 
ITCOTCK was not something I heard until much later, surprisingly enough. Although at this time, I also picked up Liege & Lief, by Fairport Convention, that still is one of my favorite albums of all time, and it there was a song that I have never failed to enjoy, is ... "Reynardine".
 
The noisy and loud stuff never got to me much, and was the part of FM radio, that helped make it commercial in those days ... sadly enough. And killed the radio waves with a lot of ... crabs!

dmbaer
Very difficult question to answer, but I'm pretty certain no matter how much deliberation, in the end the answer would inevitably be Switched On Bach.

I totally hated that album. I had already heard, by that time Tomita, and a few other things, like Beaver and Krause, and as I knew by then a lot of classical music (parents had over 3K LP's of it!!!), I thought the interpretation was ... not very good, but I did notice that it gave the synthesizer a massive jump in extending its abilities and knowledge and that more folks went after it since that moment.
 
I even had something most don't, or know ... George Harrison's Lectronic Music. Which, sadly enough is just trying to learn the knobs, and this I was able to compare to Tangerine Dream a couple of years later and realize that the noise was now becoming music.
 
And then, when Stanley Kubrick used a piece of it, I just thought that the whole thing was tasteless and not enjoyable. Hearing it today is a bit different, but maybe it was the context that it came with that took me away from it, and a lot of that stuff.

I've been thinking about this for a couple of days, trying to come up with just one. Would it be Sgt. Pepper? Or Who's Next? Dark Side Of The Moon or Grand Funk's Red Album (bet you never thought you'd see those 2 together in the same "best of" fred)? Emerson, Lake and Palmer's first?
Now craigb throws in Boston, confounding me even more.
These fred's come up every few years and I think I gave the same response last time.
Revolver.
Such a wide range of sounds and styles, pop to pschycodelia to eastern mysticism and political rants. I even like Yellow Submarine, sometimes. Great production, too.

Ya, Ya, Ya, just answer the question. It seems nobody can read instructions anymore. What ALBUM..... just 1.

For me personally it would have been Jean Michelle Jarre's Oxygen.  It had the most impact on me introducing the whole concept of electronic music and making me wanting to go out and get into it.  I have been doing it ever since!
 
Tangerine Dream's Logos was another one that came out a little after that. 
 
Just out of interest Jarre's Oxygen 3 which he released last year is also quite amazing too. Nothing like the first one but seriously good none the less.  He has not lost his touch only got better.

ampfixer
Ya, Ya, Ya, just answer the question. It seems nobody can read instructions anymore. What ALBUM..... just 1.

Exactly...
 

..that influenced/inspired you the most, which one would it be?

 
I don't think that's a hard question at all.

Dark Side Of The Moon changed everything. That one is why I picked up the guitar.
Then it was The Wall, Wish You Were Here and Animals.