Glock pistol ergonomics don't seem to be magnified for "less than large" handed people.
My first question is: do you find large gloves a snug fit or maybe even a little tight? My second question is: do you plan on using the pistol in a shooting sport like IPSC or IDPA?
Don't get me wrong, people with smaller than large hands can operate a Glock very well, but a better fit is much better at building confidence. Also, a poorly fitted pistol starts to aggravate the hand after shooting off a dozen mags in a day. Some of the ergo problems can be mitigated by aftermarket modifications, but if you plan on shooting a pistol sport like IDPA or IPSC then there are rules in place to prevent you from doing too much to your pistol.
I find medium gloves too tight, but large gloves are a bit loose. I find the squareness of the Glock grip catches me in the wrong part of the palm and causes discomfort. The M&P grip doesn't do that, it's a much more gradual radius at the grip corners. When on the clock I find it easier to maintain a positive and repeatable grip with an M&P, with a Glock it feels like I'm fumbling all the time. At the end of a match my hands feel fine with an M&P, not so much with a Glock.
So, if you have big hands and/or you just plink at the range then the Glock will probably work well for you. You can totally pimp it out into something that feels like it was designed just for you. But, if you have less than large hands (the majority of people) and you shoot many magazines in a day in a shooting sport I'd recommend the M&P.