I had an AMD 7850 for a year and it was a great card. I then upgraded to 2 AMD 270x graphics cards in crossfire configuration and while i found the performance great in games like Battlefield 4, Assassins Creed 4 didn't benefit much if at all. I removed one card and am now looking at getting a single AMD 280x.
Crossfire works great depending on the game but the 7850 will be mantle compatible and more reliable performance overall.:D