Thanks for the info everyone. I'm actually a little surprised how many people voted Hk, considering how many Glock fans are out there.
I should've mentioned that I already own an M&P9, that's why I'm leaning a little more toward the Hk, I like the idea of the external hammer and already have a striker fired.
I'm thinking that I'll go with the Hk in .40 and get a Glock 17 (Gen 4 RTF likely, seeing as there's no difference in price) a bit later on.
9mm is cheaper than .40 and I have a feeling after paying for the Hk I may want to baby it a little more than a Glock or my M&P.