I'm not the best person to asked that question. My brother had a 360, but I, personally, only played Gears of War 1 and 2 to completion, the latter being the last time I put significant time into playing a 360 game so I'm not terribly familiar with the controller. From what I remember, I liked the 360 controller though I often accidentally slipped off the face buttons and hit the ginormous menu button which isn't a problem on the Pro Controller. I like analog triggers so I wish the Pro Controller had them.
The Pro Controller annihilates the Dual Shock 3. It's not even close.