Of course there are alternative controllers available, but here's Mike Ferro's analysis on the standard 360 and PS3 controllers:

http://gamer.blorge.com/2008/11/22/analysis-ps3-vs-xbox-360-controller-comparison/

My take: Overall a nice analysis, but does not address all aspects.

For games like Ape Escape or Super Stardust HD (games I like and own) the symmetrical nature of the analog sticks feels a lot more natural and is far more effective on the PS3.

I also like the motion sensing ability of the DH3 which the 360 controller does not provide. For example the flying parts in Ratchet & Clank: Tools of Destruction or a game like Super Ruba Dub. With LittleBigPlanet you can make a lot of gestures, like shaking your head or looking at and pointing towards something when playing online with people (next to chat communication). I like the triggers, pressing them a little further you can get your sackboy to point fingers at things instead of just waving your hands for various gestures.

Although I can manage with both controllers myself, I will have to note my girlfriend and sister both got hand cramps from using the 360 controller (and not from using the PS3 controller). Of course there are others who say they experienced the exact opposite to be the case for them, but note there are hundreds of million of gamers out there who used similar controllers as those standard with the PS3.

In the end its all very subjective and depends on personal preferences. But you hear 360 fans all the time about how the PS3 controller sucks and the 360's controller is vastly superior, I thought this analysis to be an interesting read.

My opinion as a physical therapist and the ergotherapists I know is that the PS3 controller is better designed overall, it more easily fits more different kinds of hands. For the symmetrical nature of the analog sticks this is also the case, better suited for both left and right handed people, the active range of motion is a handicap for the left 360 analog stick (especially an issue if you have left-hand problems or small thumbs).

I did not expect this outcome!

I never owned a PS2, only some short playtimes on both old XBox (IMO that bulky controller simply sucks) and PS2 at friends. I had a 360 for many months, I got used to it finishing Gears, playing Tomb Raider, Dead or Alive, etc. I prefer the PS3 controller ever since I owned a PS3. BTW, I have large sized hands.

But other than that I agree, it takes some time to feel comfortable, like pressing buttons at reflex speed in games, etc.

PS3 controller. The paddle is better for PES.

The Sony controller always seemed too small for my gargantuan thumbs.

nice,,,,PS3 controller feels right due to it being symmetric.

360 also feels nice/different,,,so you don't loose either way

Amen, brother!

I think they are both fine.

However the triggers are perfect on the 360 controller.

I dont know who at Sony thought slippy convex triggers was a good idea but I pray they dont work there anymore.

Design decisions like this, Sony can do without.

I have small hands but my favourite controller of all time was the "huge" Xbox 1 controller they released with the system. The S and the 360 controllers are a small step backwards for me.

Thirded. I saw the thread title, and the poster, and knew what the outcome was going to be.

On topic: I think, Mike, if you bothered polling X360 and PS3 users to ask which was the better controller, you'd most likely get the answer that the X360 controller is the best. The X360 controller is the best (imo) controller I've ever used for traditional gaming, and most gamers that have tried both will tell you that, too. 

Convex thumbsticks (like Cypher stated) feel horrible on Playstation, or any, controllers. Even the N64 kinda got it right with it's joystick. The last PS3 controller I used (mind you, it was pre-DS3) felt like a cheap Mattel Hypervision controller - too light, with flaky triggers. The X360 controller has the perfect balance of weight, response, and features to edge out the PS2 controller for best stock controller I've used.