Logs, I own both the PX-4 and the M&P, the Beretta in 9mm and the M&P in 40 S&W. If I had to pick it would be a tough choice. The M&P feels better in the hand, narrower or better contour at the top of the grip. The PX-4 has very low recoil for a gun of this weight. There is no torque effect from the rotating barrel. I think it really comes down to the double action striker fired of the traditional double/single action. I like the M&P trigger better than the XD, the XD feels a little mushy whereas the M&P has a crisp break. I can't really compare to a Glock, don't own one, only shot one a few times.
Go with your gut on this, you'll buy the other one in a few months either way.