For sounds (VST synth...), I often use presets because I want to play quickly if I have a melodic idea.
 
For FX, I generally start from a preset and tweak it. Some plugins have really amazing presets, like the L-Phase, which have another great feature: the small description. It should be available in every plugin (synth or FX). Too many plugins show presets with mysterious names and no explanation and it's a big waste of time to try them.

I find that some presets are very good and it seems consistently to be the same companies that provide them.

Some companies obviously want their presets to have significantly more value than just menu fillers.

I usually start out with a preset that's close to what I'm looking for. Obviously it depends on the plug-in. I try not to get too caught up in the whole programming from scratch thing. It take's time away from the actual music making. Next thing you know, it's two hours later and I still have no finished music.

yes I use presets and then tweak them very gently.
 
Pro Channel presets are very helpful as starting points.

Presets. I'd rather spend my time composing than spending time tweaking presets. The average listeners won't appreciate the time spent trying to create an "original sound" and honestly you can't make anything that sounds much different from the thousands of sound already being used. But if it satisfies your creative side then that's cool. YOLO.

I have a tendency to create my own presets for EQ compression and mastering but not really for other fx based plugins.
As I change favourites I often use matching to re-create a preset from my previous favourite to the new one. I recently did this with the LP EQ, re-creating presets I had created in Waves plugins. 
These are always used as starting points though.
I tend to use stock sounds in virtual instruments with a bit of tweaking but I usually don't re-use them so rarely save them.

Most often I will use as a starting point and tweak as needed for times sakes. For EQ I always start from scratch, as it is always situational specific

Well as I recall on my old Roland 2480 one of the effects was a bunch of Roland guitar simulations . I used to like those presets a lot. With the plugs and sonar I was tempted to say presets but I do actually adjust the compression or the verb a little bit. I try not to go too crazy with the tweaks because like drinking 20 samples of IPA in a row pretty soon everything starts to sound the same.
WSS

It depends 
 
With some VSTs I use some presets as is, Omnisphere 2 and Alchemy come to mind. Most I tweak and sometimes I start from scratch.

mudgel
I find that some presets are very good and it seems consistently to be the same companies that provide them.

Some companies obviously want their presets to have significantly more value than just menu fillers.

I've never thought to compare that way, do you have any examples of companies that you feel have good presets (or the opposite)?