In my situation, my .45 option will always be my 1911's. One is a Springfield Mil-Spec that has had about $1500 of work done to it, wasn't needed, it ran great just the way it was but I wanted more. My other one is a 1943 Ithaca that my grandpa carried in Korea where he carried it while he drove and operated a tank. I'm a Glock 9mm, 1911 .45, S&W revolver guy. Those are the only handguns I deal with. However, I am also a M&P certified armorer and as much as I love Glocks, I think Smith makes a much more comfortable .45 ACP pistol. Both the Glock and M&P are reliable, I don't really care for all the extra parts inside the Smith to make it do the same thing as the Glock but it feels better in the hand and shoots better for me as I have slightly smaller hands.
So, if I could not have a 1911, I would choose an M&P .45 and that's not to say that the 1911 is better, I just prefer it, but if we are talking about daily carry polymer .45's, then I would chose the M&P. Plenty of mags, holsters, etc.... for that platform