I've been using mostly AMD since a K6 550MHz. AMD CPU was considered fast.
Still, while I like AMD, I see too many people that just don't understand the importance of the video card over the actual CPU for such applications as high level games and video encoding/editing. I've seen too many people get the best available CPU, loads of memory, and then spend $100.00 on a video card. Then they can't figure out why they can't run a game at high video levels or frame rates. For such apps the video card is often the most important factor as to game/encoding/editing performance.
I remember back when I was running Windows Vista I had a 1GHz. AMD CPU with only 1GB of memory and wanted to look at a game demo version (playable to a certain point; think it was Halo.). The minimum requirements called for a 1.5GHz. CPU and mine was only 1.0GHz.. The thing was that I had a superior video card for the time, actually two cards; one PCIe and the other
AGP. The game demo version worked just fine at the highest video levels proving that the video card was the more important factor.
The bottom line is that, if going for gaming or video stuff, you are probably going to get more performance with a $400.00 CPU and a $600.00 video card than with a $600.00 CPU and a $400.00 video card... The performance difference is not necessarily according to the prices I listed; just examples. The point is that if you have a choice to spend high bucks on either a CPU or a video card, but not both, and are a gamer, or do video stuff, you are probably better off spending the money on the video card.