You gotta shot them all and pick what fits you best. There's a gun range in Louisville that rents out different handguns for $10 a session. I'm certain there's something around where you live where you can do the same. Rent one of each and have a big day.
(After all the positive M&P feedback, I'm going to look at one myself.)
(After all the positive M&P feedback, I'm going to look at one myself.)