No, can't go wrong with either.
I have both and like them both and here are some particulars of each brand:
- If you want to shoot lead reloads, M&P barrels are better suited due to conventional square cut land/groove rifling vs Glock's rounded hexagonal rifling with longer leade that tends to build up fouling fast and require frequent cleaning around 200-300 rounds. With M&P, I can shoot lead reloads all day (500-1000+ rounds) without issues.
- You can get 40-9 conversion barrels for both to practice with cheaper 9mm and carry 40S&W.
- Glock mags are probably the cheapest of any factory mags (in terms of price, not quality) and they work well.
- As posted already, M&P pistols have full ambi controls (slide lock, safety, mag release) for left handed shooters.
- M&P has small/medium/large grip inserts for better fit and my wife's small hands are happy with full size M&P45 using small insert. M&P controls are very ergonomic and offer more "natural grip angle" regardless of shooter/hand size.
- IMO, M&P captured recoil spring sets with stainless steel full-length guide rods offer softer felt recoil. But my Gen3 Glock's captured recoil spring sets offer softer felt recoil than most other factory stock pistols. Replacement Glock recoil spring sets are cheaper (
around $8).
- Glock's loaded chamber indicator (bump on the extractor) works better for me than M&P's hole on top of barrel hood (if the hole gets dirty, you can't see as well).
- M&P trigger can be modified to provide probably the best striker fired trigger I have shot either through Apex Tactical parts replacement or trigger job -
http://www.burwellguns.com/M&Ptriggerjob1.htm
- Glocks are very easy and faster to field strip for inspection/cleaning.
- IME, new shooters I have seen/helped produced the smallest and more consistent shot groups with Glocks than most other non-1911 factory stock pistols under $1000. New shooters obtained smaller shot groups with my M&P45/trigger job than stock Glocks. (I have not seen the M&P models with the new S&W triggers yet so this may change in the future
).
- M&Ps are made in the USA and Glocks are made in Austria.
All in all, both are great pistols and I would not hesitate to grab either to defend my life or the lives of my family in a moment's notice as they have been very reliable and accurate.