The question remains, are you asking from Free America, or from within the People's Republic?
Assuming that we're not discussing a MA gun, here are my thoughts:
The M&P has a terrible trigger, even without the 10lb MA requirement. Of course, there are some 'smiths out there who have a great reputation for solving this problem, but any gun loses points if you have to add $150 of gunsmithing & shipping to the price tag.
+1 GLOCK
The M&P has amazing ergonomics, especially relative to the GLOCK.
+1 M&P
The GLOCK has a proven reputation for reliability, whereas the M&P is still unproven. That's not to say the M&P is unreliable (I've yet to hear a report of issues), but GLOCK has 20+ years, while the M&P has been out 1 (?) year.
+1 GLOCK
WARRANTY
You can't beat S&W's lifetime warranty (actually, isn't it two lifetimes now?).
+1 M&P
Bottom line: Both are reliable tools which perform well. Some people have an emotional attachment to GLOCKs. Some people love the ergonomics of the M&P. So go shoot both of them and ask yourself, which model are you more comfortable carrying/holding/shooting?
Interesting MA notes:
If you get the M&P, you'r probably going to want to send it to a 'smith, regardless of whether it's the MA model or not.
You cannot buy new GLOCKs in MA, so you'll be getting something with an unknown history. How many rounds, modifications, refurbished, etc will be unknown. Also, you'll pay a MA premium for a GLOCK.
M&P mags will be NEW (and for a limited time you get four mags with a M&P purchase), but limited to 10 rounds. Preban high-cap GLOCK mags are available, but there's a lot of grey area as to whether or not they're actually preban, and along with the gun, they're used.