For single cards, AMD is fine, but for two or more, SLI generally works (scaling varies) but Crossfire does not. If you are interested in running multiple graphics cards, I'd suggest going with nVidia unless and until AMD fixes Crossfire.
You may want to get some low-profile RAM to avoid possible clearance issues with the heat sink.
As to that, the Xigmatek Gaia cools within 1C of the Coolermaster but is 6db quieter and is only $20 at Newegg. Both of my rigs use them, and they work well for me.