Rumble and weight like everyone else is saying.

I would trade my DS3 for a Sixaxis anyday.

Rumble, weight AND anaolges (dont break as easy) . Also the dualshocks have a better matte finish so there isnt finger prints left on the controller, while the sixaxis collect fingerprints like you wouldnt believe.

Why? Thats a ripp..

Rarely use the rumble, and miss the lighter weight. I used to marvel at how light my sixaxis was compared to my 360 controller, not the difference isn't that significant. If you go from 360 controller to sixaxis it feels so damn light :) 

I've been through 2 sixaxis controllers because of the trigger buttons falling off or the L2 button would stick after pressing it down all the way. When the DS3 came out I immediately got that thinking it would be more secure in that area; and it was. My DS3 still works great after a year of having it, so I always think of DS3 being way better than the sixaxis.

One Rumbles, one does not

One isn't heavy enough for my taste and the other SERIOUSLY needs to put on some weight before I consider touching it again.