I have held the SR9, and because I OWN a P95 and feel the grip is just right (with a Hand-All to boot) I think the SR9 is too thin. The pistol however, after about 2-300 rounds and with the mag disconnect removed, will never give you a problem. They are, like all Ruger centerfire autoloaders, VERY reliable. I like the XD grip and think the XD is a great pistol, but WHY do they use that flat slide release? It's one of the reasons I don't like Glocks!If you have held a P95 or P944 or the .45 older variant and feel the grip is too thick take a look at the SR9 if you can.
Of the three, my personal fave is the M&P; it's very comfortable to hold (I'd probably put a Hogue on it as well though, but that's me), easy to manipulate, pretty decent barrel axis, and slim enough that even though it's just smaller than full-size it will conceal at 1, 4, or 6:00 without much effort. The 9mm is a double-stack 17-round like the SR9; if you want heavier rounds you'll sacrifice capacity of course. It's still a stamped slide release but not flat, so it's far easier to manipulate than the Glocks and XDs I've tried.