Clock per clock, in gaming, they are nearly identical. This is why most just opt for the AMD to save a buck. I personally just like i7's in general. I believe they are superior processors overall and why not use the best, right?
However, you could get an AMD that is stock 3.6ghz or something and overclock it beyond a stock Intel and in that case the AMD could very well be faster in games. Especially those RTS type games.
It's a general question you've asked but there are a lot of answers for it and one could skew the the discussion towards either brand.