I love my gun(SW MP .40c), it fits my hands perfectly. It shoots very accurately and its got some good capacity for a .40 compact. I have had the unforuate luck to get a pistol with mag drop issues. I was just at the range tonight after replacing the magazine catch with a new one SW sent me. After 30 rounds my gun started dropping again. So it looks like i'll have to send the gun back to the factory. From all accounts this is happening to a small amount of compact owners. It doesn't seem to affect the fullsized owners.
So even with my problems i still have to go with a MP over glock or XD. I've shot an XD and completely did not like it. It is just like the glock grip, that is to say like holding onto a plastic square.
Best advice, go down to the range and rent all three guns. You might fall in love with the glock after you shoot it.