What fits your hand the best would be my choice. Personally I like the feel of a Gen 3 17. If you haven't shot one I'm pretty sure that ITP has a 17 that they rent, I"m not sure about an M&P.
[FONT="]NRA Life member [/FONT][FONT="]GSSF member[/FONT]
[FONT="]Gunsite graduate Certified Glock armorer[/FONT]
[FONT="]1911 Mechanic[/FONT]
Beretta 92/M9