The Playstation 3 Six Axis Controller may not fit your hands as well the Xbox 360's, but it is still a very good controller.
For one thing, it has Six Axis, which means it has motion sensitivity. Although its barely used, their are still some great possibilities. Games that use this can be really fun and intuitive.
An even better quality is that it comes with a USB cord and port. This allows you to charge the controller through the PS3, which is really convenient and I wish 360 controllers would come with. The battery gets charged decently quick and it last amazingly long. What also makes that great is its computer accessibility. All I had to do was download one simple, small file, plug it in, and it was ready to play computer games. I whad wanted to play my computer with an Xbox 360 controller, but no USB and my signal reciever died, so I had this great product to back it.
It's last great quality is it's durability. I've dropped this controller thousands of times and it's still in great working condition. Its been soaked, stepped on by heavy people (my brother), slept on by heavy people, tossed, banged, and dropped some more, but absolutely nothing is wrong with it.
So if your looking for a good computer controller, you might want to consider this one.