I don't buy much into XFX's double lifetime warranty because I usually keep a video card for only several months and I never register the warranty anyway. So whether there is a double or single lifetime warranty makes no difference to me. I'm not gonna pay extra for that.
As for EVGA, I've never owned a card from them. I know they have that trade-up program but again, I swap video cards like underwear so if I want a new card, I'll go to the local store and get it today instead of waiting for mail. I find EVGA cards are especially extra expensive but with only average or below-average specs.
My vote goes towards BFG. In my opinion, they are still one of the "premium" nVidia card makers but they offer the perfect mix of factory OC-ed cards at a REASONABLE price. I've owned an 8800GTS 320MB from them I think.
On the ATI side, Sapphire is the way to go. They're usually the cheapest and I have never EVER had a Sapphire card go bad. Their cards have always OC-ed at least average if not high compared to other brands and the standard 1 or 2 year warranty is good enough for my 3-6 month ownership of the video card. I own a Sapphire 5870 Vapor-X even now. :bleh: