#1 you are paying for the company's support. The cards are for the most part all made by the same place. Every once and a while Asus or Gigabyte will make their own board for a special edition of a card. Other will replace the factory cooler with a different, and most cases better one. But for the most part they are all the same with some BIOS settings for that brand. Some set the fan profiles different. Some allow for voltage tweaking. Factory overclocks are also set this way. But given everything looks the same, it most likely is. XFX is sorta tagged as having the "best support" they are great and have a lifetime transferable warranty. However, many times you pay more for that. I usually just want a 3 year warranty because won't own it any longer than that. I like Asus and their support has always been great. Granted I had to RMA a card 4 times, but they made it right in the end.
Just read the review for a card on Newegg. Just remember to weed out the ones where people just rant. If a card has a ton of bad reviews, stay away. the HIS IceQ is in my opinion the better coolers that are installed by factory. But they are not always needed unless you want to OC.