I don't know much about XFX but eVGA has a lifetime warrenty, even if you change the stock cooler and some overclocking. And they also have their step up program as well which will let you get a better card within 90 days of your purchase. I choose eVGA personally.
But to be fair, I don't know much about XFX so I would wait for someone to mention them before making a decision. Hope this helps.