For me it has gotten very simple. Late model GEN3 or GEN4 Glocks especially the G19's are having all kinds of problems. It is not myth, internet rumor or whatever. I bought one Glock and after not being able to fix it they sent me 3 (yes 3!) replacement guns.
Two had problems right out of the box. The other two broke down at 800 and 2000 rounds. After trying all the aftermarket fixes I traded it on my M&P 9c which has given me zero problems. My older Glocks work well and I will keep them. But the Ergo's aren't great for my hand. Had a couple of grip chops done and it helped.
The M&P has great Ergo's right out of the box. Put in the APEX Defense/Carry set up and it has the best trigger out there of any polymer pistol I've ever shot. Lots of LEO's in my area switching to M&P's. Just a better all around gun IMHO.