We weren't able to include benchmark results for AMD's FX family, unfortunately, because our Canadian lab's Socket AM3+ test bench died during testing for this piece. You can expect the FX series to perform roughly on par with the Phenom II, though.
Intel’s Core i5-2500K takes the performance crown, though the advantage won't necessarily buy you a better experience, since even a 2 GHz Phenom II X4 yields fluid performance paired up to a Radeon HD 6950.
A dual-core Phenom II running at 3 GHz has no problem with Mass Effect 3.
It's interesting, though, that the difference in minimum frame rate going from the bottom to the top of our performance charts is almost 2x. There does appear to be some scaling that takes place in jumping from two to three to four cores, but absolutely no gain attributable to the six-core Phenom II X6.