While a good warranty is always appealing, esp. with the outrageous cost of vid cards these days, the warranty is only as good as the future of the company, ie. if the company goes under ... And the vid card biz is a notoriously vicious industry.
Also consider, in the future if you have to utilize your warranty, your exact card (GPU) may no longer be available and you will receive an "equivalent" card at their discretion. While this normally works out to your benefit, sometimes it doesn't ... ex. you RMA a 7900-series and get an 8600 in place.
Finally, most major credit cards offer some sort of warranty "protection" service as one of their cardmember benefits. My VISA Platinum cards, for example, offer extension of any warranty for up to a maximum of 3 years. I've used this service more than once, and normally come out even or ahead on my money. And for some purchases, they even offer extensions to their initial extension, though at a cost. But it can be a good deal still, I was able to get a 5 year warranty (total) for my Sony XBR for $97 !