I have run an XFX for my last 2 cards. My 5770 is 4-5 years old now and still running OCed with out issues and this is a reference design.
I am currently running an XFX HD 7970 DD ghost version. The card runs great but I did up the fan arch to help keep it from throttling. This is just a pet peeve of mine, the fact I want to keep my temps as cool as possible. the one draw back I found with the HD 7970 was the fact XFX locked teh voltage control for this card which really hurt the OC ability. The HD 280X is just a rebadged HD7970. The 290 is a fresh completely new GPU. XFX is also OK to deal with for RMA and support.
Asus can be a pain from time to time for support But all in all very reputable company and makes good part but so does XFX and they have been for years.
Price vs the performance boost I think it is worth getting the 290