Depends what you plan on doing with your card. If you want to mod or OC it - then XFX has the best warranty. Maybe a new card is coming out soon and you want to upgrade once it comes out? Then EVGA is for that with the "step up" program - They also offer a lifetime warranty with their cards. If you just want a card to toss in your systems and forget about - I think just about any brand would work. I would still go to the manufacturer site and check their warranties, because it's always nice to have at least a 2-3 year warranty.
Does brand matter? Yes and no. In terms of the quality of the hardware, when dealing with stock vanilla cards, they're all reference boards and built by NVIDIA (i.e. all identical). But you get added value with the special programs that some brands offer, like lifetime warranties or trade-in programs.
With that said, Palit has absolutely the worst "warranty" (if you could call it that) I've ever seen in my life. Here it is in its entirety:
"If you did not purchase Palit's products directly from us, please contact with your direct vendor for RMA service."
And if you DID buy it directly from them, here's the address you ship your defective card to:
E & A LOGISTICS CO.
ROOM 4-6, 11/F.,NAN FUNG COMMERCIAL
CENTRE,19 LAM LOK ROAD, KOWLOON
BAY,KOWLOON, HONG KONG
Unless you get an unbeatable deal, I would stay away from Palit if I were you. I know this because I panicked and bought a Palit 8800GT and now it's making strange noises and I have no recourse.