It is hard to over generalize. Since I switched from Apple II's to PC's, I had always used Intel, with the exception of a Cyrix computer in mid 90's (big mistake).
However, in my last computer, I was set on an i5-750, but looking to i7-930 (because of multi-threading), as I do a lot of video encoding. Right before I pulled the trigger on my new system, the AMD hexacores came out, and I ended up getting a Phenom IIx6 1090t.
It does very good in video encoding, and has great benchmarks in Handbrake, which is my favorite encoding program (along with XVID4PSP).
So you should take into account what your needs are and buy what you are comfortable with. http://www.tomshardware.com/charts/desktop-cpu-charts-2010/Video-Transcode-Handbrake-MPEG-2-to-H.264,2421.html