My vote is for the M&Pc.
These are two completely different guns. For self-defense firearms, I personally prefer to not have an external safety. I haven't held a PX4sc but it definitely looks clunky. There's a member on here that has one. Do a search and you'll probably find the thread with a picture in it. Try to rent and shoot them both if you can.
Also, the market for accessories (holsters, mags, etc.) is much larger for the M&P.