I own a Springfield XD9 4 inch, and it shoots like a dream. The weapon is a natural pointer, and is on target. Recoil is minimal, and the sights are easy to pick up.
I have no experience with the M&P, but I would imagine that it would perform with the same quality as the Springfield. Springfield does have the advantage of having alot of package items along with the pistol (holster, mag holder, bore brush, etc...)
Which one feels right in your hand? Answer that, and you have your first weapon picked out.