I guess since it takes so many more parts and effort to make a Glock work and feel as good as an M&P out of the box, totally makes sense more stuff available. So let me rephrase, both great guns, but with the Gluck, you get to buy more aftermarket parts to get it where it runs as good as an M&P, which also helps our economy get back on track. So buy a foreign made gun, then spend more on accessories, but please make sure those are Made in the USA. OR, buy American made M&P.
Make a Glock work? I'll give an example of the degree Glocks are held to. My first major match I let my slide rub a barricade which slowed my slide down yada yada yada. As soon as the range was clear TGO ran over and, demanded if that was a Glock and what happened. Glocks sometimes will have a problem. Any of the Glocks I have sold or have except for a NIB 35 and a used 23 I have only ran a couple mags through have multiple times more rounds through them then has been mentioned here and at times no cleaning for a couple of months of near constant shooting. I went over 5000 rounds when I had the chance to see if the hype that was being written was true - all this in the desert. Make a Glock work? Please don't insult anyone or mislead others. Until such test have been performed with other pistils over many test samples and documented we don't know if any are as good as a Glock, but we do know they run and there are no serious problems with them that have came to the attention of the shooting public. I recommend Glocks, XDs and M&Ps as well as the 39/59 series, CZ and Sigs. Though for me Glock is what I use and believe in. A Glock is not for everyone and I am mature enough to know this and wise enough to suggest to try before one buys. I let others make their choices based hopefully on their shooting experiences with different platforms/makes & models. Not mislead
Which is better for the shooter depends on the shooter. Many at my old club started with Glocks and moved to XDs. There are many more XDs in W TX and e NM than M&Ps and they run as well, so don't over look the XD line.
To make a Glock competitive you shoot it. To make it better, sights. To tune it - recoil spring. To be cool add a mag well. You don't have to tune Glock mags nor be a fanatic cleaning them between each stage (conditions depending of course) like some mags. Glock even makes a factory 22 round 40 mag supporting the competition shooters. Glock further promotes the shooting sport with GSSF which doesn't make their pistol better but shows the company is behind shooting.
As stated Glocks have a lower bore axis. Does this matter some would say yes and physics would as well, but my favorite 45 I don't own anymore is a Sig 220 which has a high bore axis.
As stated shoot as many as you can and make an informed decision.
Ref mags there are many that are versions of the Glock mag and AFA seeing a double feed because a mag did not drop free hummmm Love to see it, but never have. I also don't understand. If you are changing mags then why is the gun cycling? And how does it double feed with a single cycle and a slightly lower mag? Like I stated would like to see it, Sounds more operator induced to me than a gun related problem or weak mag springs which is a general maintenance issue I have seen the Glock shake

and used to be good at it until drop free mags came out. I even used to have my 26s mags drop free when i was shooting it all the time, but in CCW match last yr after not shooting it for a great while I had my hand in the way - my fault not the guns.
Anyway to the OP shoot-em and decide. All three series are good pistols.