Federal HST 180gr in my opinion. They are supposedly LEO only, although are available from some civilian sources. Nice gun by the way. I put two mags of HST's through my M&P this week and had no problems. Why do I like them? They expand to nearly .80" in most tests while still penetrating about 14" in most tests in ballistic gel. That seems to be the best performance around.
Also, I did a very similair thread to this last week:
Although I'm sure that's just one of dozens on this topic here at the TFL.
I think cor-bon DPX's would be my second coice, remington golden sabers third, and Speer Gold Dot II's fourth.
check out these links: