If you plan to upgrade your video in a year, then I would go for the 4890 to have the power NOW. It is DX10.1 and consumes more power, but does have more raw performing power.
If you are planning to hang on to this card for a while, or are limited by your PSU, I would recommend the 5770. It is DX11 and runs cooler and uses less power.
As far as manufacturers, The cards are all the same (maybe a different cooler), but the difference is support and warranty. XFX tends to be the best in that department. My last 2 cards have been ASUS, which has a 3year warranty. I don't ususally hang onto a card that long anyways. But really it is whoever has the best deal.