The subject of factory presets and soft synths was broached in this thread but I thought it would be worth extending the discussion. I still feeling I am cheating when I use an unedited preset. (yet if it work in the track, why not?)
 
I started my experience with hardware synthesizers with an EMS synthi A when the idea of a preset was a distant dream. Now a software emulation of that synth is subject to scathing criticism for not having many good presets.
 
Several years later I owned a Roland SH101 and MC202, again no presets, but like the Synthi A there was a patch book showing settings for various sounds, a consensus was this was for the salesman so he could demonstrate the product rather than for the serious user.
 
When I got a Yamaha DX100 and a Korg Poly 800 (I am not sure in which order) I entered the preset world. The Korg followed a familiar architecture so I was pretty happy tweaking it, but the Yamaha took a lot of getting used to, and once you had mastered what was going on the mechanics of programming on the tiny LCD was a pain, so a lot of the time I tended to stick with the presets, while at the same time thinking of it as a bit of a cop-out.
 
So with software synths I have few problems setting up sounds I am thinking of on my favourite analogue emulations, Minimonsta, Korg Monopoly, XILS4 or the Arturia Oberheim SEM V.
 
I was put off more modern synths like Z3Ta by the predominantly EDM style presets. It took me a while to get under the hood and work out how to roll my own patches. I think I know my way around reasonably well now but the wave shaping is still a process of trial and error. It is a very versatile synth once you take the time to learn about it.
 
I did buy a couple of Nori Ubukata Historic Synth Giants preset packs for Synthmaster. These are nothing short of excellent sounding exactly like the synth voices on the track he is emulating. And therein lies the rub, they are so close that without tweaking they are of little use unless you are doing cover.
 
I think the most useful types of presets would be basic ones, devoid of effects, that provide a good starting point from which to customise your own sounds.

For me it doesn't take long with a preset for a little mangling (in ignorance) to make that preset completely unrecognisable.

I'm grateful for them to give me a start. It lets me quickly audition sounds when I'm looking/listening for something in particular. Noodling with virtual knobs, buttons dials and sliders maybe fun for some but I don't mind standing on the shoulders of those who did the work to create them. I don't think it's cheating. I mean you wouldn't call a pianist a cheat if the instrument he plays sounds particularly good just because he didn't make the piano that creates the sound.

I buy a synth as much for the presets that come with it as the synth itself because honestly I couldn't make the sounds I want from scratch, same as I can play guitar but certainly couldn't make one.

I have the best excuse - I'm a guitar player. :P
 
 
Songwriting, arranging and engineering/mixing are the skills I really work on - and all that goes w/ it, like basic studio acoustics and such. I'm really pushing to try and get certified for Logic AND if all goes extraordinarily well, Pro Tools.  I have more than enough on my plate.
 
So presets are an essential part of my workflow, and I say it w/o any shame. I try my best to make them my own by customizing a tiny bit, but that's no always an option.
 
I do spend time learning a bit more about my synths semi-regularly. I can create my own patches on certain simpler synths, like Korg Poly Six and Steinberg's Retrologue, which I really love to mess with. But in all frankness, I don't really master that art - I just got better at creating happy accidents.
 
One synth which really helps me improving is Logic's Retro Synth - that one allows me to switch back and forth between subtractive, FM and wavetable type of synthesis while maintaining the same basic type of interface and the same layout.
 
The time I spend tweaking pays off when I have to modify a patch, because I at least have a vague idea of what to tweak.
 
Some synths like Z3ta I really dig but I'll not master in this lifetime. But that's okay - I'll be happy to focus on Mini Moog type of synths.
 
As for presets themselves - it's surprising how drenched in effect most of them are. In fact, many patches in Z3ta are clipping. Another thing you have to be very careful with is stereo imaging. Sometimes you don't immediately notice it because the preset sounds relatively simple, but when you pay attention a bit, you notice how wide it sounds.
 
All of my old Sonar demos suffer from that same problem - because I was working fast AND didn't really know what I was doing as far as mixing - neither did I have the set up to really hear it. Effects and stereo imaging issues all over the place.
 
Some of those patches I really liked but had to give up on and replace because they just wouldn't sit in a mix, and once cleaned up, they sounded pretty weak.
 
A lot of people badmouth the synths included in Logic and say they sound sterile - imho, that's precisely because they sound dry for the biggest part. Not always the most inspiring, but as the tracks pile up, you still maintain a solid and coherent mix - and then you can put on the icing on the cake.

A good set of presets should have good covers and also show its potential.

The choice is individual. Some people like to learn how to bark. Some people just buy a dog.

Woof woof!

Rain
 
Some of those patches I really liked but had to give up on and replace because they just wouldn't sit in a mix, and once cleaned up, they sounded pretty weak.
 
A lot of people badmouth the synths included in Logic and say they sound sterile - imho, that's precisely because they sound dry for the biggest part. Not always the most inspiring, but as the tracks pile up, you still maintain a solid and coherent mix - and then you can put on the icing on the cake.

That explains better one of the points I was trying to make when I said "I think the most useful types of presets would be basic ones, devoid of effects, that provide a good starting point from which to customise your own sounds."
 
Presets can be a good starting point, usually the first thing I do with a preset is turn off any effects, then work on the wave forms, filter and envelope settings to get where I want it to be, and then add effects at later stage.
 
Perhaps illogically, I look at soft synths differently from ROMpliers and sampled instruments. Maybe because I learnt to program analogue synths long before I could pick out a few chords on a keyboard.

Too many effects on presents annoy me. Removing them can reveal the synth isn't doing so much. I'd love a global fx off option on a synth so I could run through it and listen to just the synth. Often the FX on presets are laid on too heavy handedly for my tastes.
 
The basstation Keyboard had just 7 memory locations, and buying the rack version opened up 60 memory slots. Many dissed the basstation, because they wanted it to be a TB303, and calling it a 'bass'station gave the impression that was it's strength. It could do bass, but not deep bass. It was a good synth.
 
If stripped back to just one analogue, to get back in control of it. The presets will give me an idea of what to look ofr from it, but I'd probably build each sound from scratch, making a vanilla patch I can call up to start from each time

I love presets. Like the OP, I grew up with synthesizers that had no memory beyond wherever you left the knobs yesterday. My presets were handwritten entries in a spiral notebook. 
 
Factory presets are important because they let you know what the instrument is capable of. The best presets provide you with a set of templates from which to start programming. I keep a folder for Zebra called "Templates" that consists of generic basses, pads and plucks with minimal effects or fancy techniques. Whenever I create a new patch, I start with one of those. Half are original, half have been adapted from commercial presets.
 
Presets are also a training manual. Much of what I know about programming Zebra I learned from Jospeph Hollo, by picking apart his great PadsHeaven 1 and 2 patches. And of course, Howard Scarr's great factory presets.
 

Being a guitarist, my music generally centres around the guitar, and the softsynths I use are basically as backup instruments I can't play. So the presets are a BIG part of my needs as I don't have the patience nor the time to customize sounds. One day, I'd really like to learn the inner workings of synths, but for now I only need quick results that might need minor tweaking.
Otherwise, the whole song creation process/inspiration will get sidetracked and I'll end up loosing focus with my primary objective.  

Plugging a Les Paul into an Orange amp is a "preset." Of course it's what happens next which defines your music. No different with synths. I don't see anything wrong with using most presets, but you'd be mad not to tweak a little it if tweaking it makes it fit the track better. The exception being presets that contain some kind of melodic or rhythmic sequence - then you're getting into sample territory. 

90% of the time it's presets I use.
 
it really depends.  If I am using my Korg M1 or Wavestation plugins there are presets I avoid cause they are used by everyone (M1 Piano anybody?).
 
Generally it's about the music and how it all sounds together.  I don't worry about it to much.
 
There are presets on my hardware synths that I avoid and will not record at all, though I like the sound.  D50 Phantasia is one that comes to mind.