Why do you mention an aftermarket cooler? For overclocking purposes?
In my opinion, AMD offer you bang per buck, but as far as I know, the i7 processors blow away what AMD have out at the minute.
That said, if you are generally just gaming, the CPU's from either won't lower performance as long as they are comparable.
Certainly don't assume for example that clock speed has anything to do with it, because it doesn't