Good call on the gen 4 19. It has become my 2nd favorite Glock, ever... surpassed only by the Gen4 G21.
I will say that in regards to the M&P... reliability I have seen has been totally on bar with Glock. Yes, the factory trigger is aweful.. however... if you drop in the full Apex Tactical DCAEK trigger kit for under $100... it becomes one of the best striker fired triggers on the market. In my opinion, only surpassed by the Powder River Precision complete match trigger kit on the XDM... but I wouldn't carry my XDM with this trigger. It moves about as much as a 1911. Beautiful and easy to shoot well with... but leaves no room for error.
With the DCAEK kit, you still get some take up, but it's perfectly smooth, and you can tell right when it's going to break. They also have the RAM kit, which will give you that same tactile and audible reset 'click' that you're used to on the Glock.
They are both great guns... I personally prefer the 19 because I'm more accustomed to the platform... but I have zero complaints about the M&P after you fix that factory trigger. If they shipped with the APEX kit from the factory, I think they could easily charge $100 more for the gun to cover the cost. Just my 2 cents.
Glock 19 G4 Gray | Glock 17 G4 FDE | S&W M&P 22 | S&W M&P 45 | S&W M&P 9 | S&W M&P Shield 9
Sig P226 MK25 | Sig P229 Extreme | Sig P320 F | Sig P320 C | HK USP 9 | HK USP 45 | HK USP 45 (Tan) | HK VP9
Daniel Defense DDM4 V4 | Arsenal SGL 21 | ASA SBR | Savage Mark II FV-SR
Mossberg 590A1 20" SP | Mossberg 500 Cruiser