For fantasy / fiction purposes, with the standing up of a militia where there was no expectation of weapons support and where each had to provide his own, I'd probably say a Glock 20; hard to argue with 15 rounds of 10mm, and the total weight would still be less than any of my 1911s.
Otherwise, I go back to my original point: whatever I like best out of what is supported.
Otherwise, I go back to my original point: whatever I like best out of what is supported.