Don't know, from what I heard the S&W m&p pistol series are great guns, although I never fired or handled one. He likes his gun and theres nothing wrong with that. Has he ever shot your 19? If so, then you did all can do you my friend. Just be glad he ain't preachin a high-point or sigma, then I'd be worried.
The M&P9c doesn't compare to the G19 though lol. The G26 yes. I think its probably because they are both a "compact" model. Even though Glocks compacts are in between most full size and compacts from other companies that I've seen.
They are all awesome guns. We have a G19, M&P9, and a M&P9c in the house. I haven't shot the 9c yet as we just got it, but the 9 is a great gun. The 9c feels great in my hands, and I'll be shooting it in a few days.
I've owned several M&Ps and while the ergos are very nice and I wish Glock would change their grip angle I keep coming back to Glock. The M&P is a very nice design and it shoots great (as long as you have a APEX trigger), but they don't have a gun yet that is a true compact sized gun like the G19/G23. Their version of the compact requires a pinky extension on the mags to get a full grip and I'm not a fan of that. Their full sized guns are very nice, but they require another $100 in trigger mods to even come close to a crisp Glock style trigger.
There are a lot of Polymer striker fired guns on the market right now that are all deserving of praise. One I am looking at right now is the new FNS 9 from FNH and the Walther PPQ. Glock still has a leg up on the competition because they are still affordable and easy to work on. Parts are cheap, mags are cheap, and they are just simple and reliable. While other gun makers spend a lot of money and time trying to add gizmos and safeties to their guns to set themselves apart from Glock, the Glock still maintains it's simple design, which I prefer.
Some folks just have a hard time letting go of brand loyalty and when it comes to Glocks they have been king of the mountain for so long everyone wants to knock them off.