I'd just buy whichever one's cheaper. I used to always go with the "higher quality" cards like EVGA but I was able to snag my Palit 460's for a great price so I took a risk. These cards don't hit above 72*C in SLI at the stock settings while playing BC2, BF3, and Metro2033. The only thing I've done thus far is to plug my monitors into the bottom card and to create a custom fan profile using Afterburner. I've got the regular Palit edition so there's no VRM cooling but I ordered some heatsinks from DealExtreme for an extremely cheap price. I also plan on putting a fan attached to the end of the GPU's so that it's blowing in between them which should take another few *C off.
Also, we all talk about the "lifespan" of the cards but in the end when was the last time you actually held onto a card until it died?