I'm an Intel fan.. only because all the Intel processors I have seen have higher L2 caches than the AMD processors I've seen.
I imagine they are both equally good, just compare specs and prices before you buy and decide based on that.
I read this a lot, and I can understand where this comes from. However, due to the differences between the way Intel and AMD processors are designed, a higher L2 cache in the Intel chip does not always mean it is superior.
At any rate, AMD seems to offer more power for the price. If you want a tri- or quad-core processor at a decent price, go with the AMD. They are reasonable, even compared to dual-core Intel Core 2 Duo processors at the same clock speeds. This is what AMD really has going for them: you can get a great processor for a reasonable price.
If you want the best performance, go with Intel. Their Core 2 Quad and Core 2 Extreme processors are second to none. But you definitely pay a huge premium; a top-of-the-line Extreme can run you around $1000.
For a while after AMD 64 came out, AMD had the performance crown. Intel processors at far greater clock speeds were beaten in benchmarks by AMD processors that by the numbers should have been slower based on the way we used to think about processors. But then the Core microarchitecture led to Core 2, and Intel has regained their performance crown by means of its R&D resources.
Personal preference may also factor in. Personally, I prefer AMD, and have never built a system with an Intel processor. This isn't to say that I won't, I just have not so far.
.