Given that it will be your first handgun, and that I don't know what kind of shooting experience you have. I would say you need to hold both, point both, possibly shoot both if you can and then make a decision. At the very least I would be visiting a shop and holding them.
I know my M&P's trigger left a bit to be desired, however at the time i was comparing it to my hunting rifles as i hadn't shot a lot of handguns before. This is like comparing apples to oranges... I bought the my Smith Range kit over the XDM, Glock, and CZ85 because of how comfortable it felt in my hands. I've got bear paws, and some handguns just do not fit, the 3 backstraps that came with the M&P let me fix that, and still be able to let the Mrs. shoot it with a 30 second change of backstraps. Bang for buck, a M&P range kit will win, hands down. The trigger has gotten better through use, and the APEX kit is about $100 if it's that big of a concern.
I can't speak for the PPX as i haven't even held one.
