Durability is the number one thing I look for because I beat the piss out of my controllers. I've had 2 of these rumble pads. The 1st one I spilled Coke on, making the buttons stick, and I had to open it up and clean it out at which point it was fine. Fine untill a week later, my Lou Brock autographed baseball rolled off my bookcase, fell 5 feet, and landed directly on the fancy little Logitech logo on the middle of the pad. The pad was toast.
I immediatly ordered a new one. That was four years ago and I havn't had a problem since.
ps I honestly think Lou Brock's autograph was the deciding factor. Had it been Ricky Henderson autograph I'm sure the pad wouldn't have broken!