i own a couple of each Glock and M&P.
both have functioned flawless for me.
at the end of the day i prefer the M&P for feel/comfort/shootabilty.
as mentioned above, why would i willfully want to shoot something that does not feel good in the hand?
that said.... i think im more accurate with my G17 than i am with my M&P9.
but that is probably just my mind teasing me because it knows i like the M&P better.