I personally use a Gigabyte Windforce R9 280X. It comes OC out of the box so you don't have to do it if you're not into that kind of thing. So far it works great but can get a little noisy at times if working at full load. That was 6 months ago so many new cards might have come out during that time. I also heard the R9 290 that came out shortly after 280X is a better value for its buck. You might want to look into that.

Also, consider that the general consensus seems to be that Nvidia seems to give better performance than AMD while AMD is priced more competitively. You might want to take that into account. Good luck!