I didn't vote in the poll due to two platforms not being in consideration.
The first is the 1911 for concealed carry, home defense, target shooting, plinking and what-not. The second, and would be my first choice if I could only have one handgun for everything with a caveat, would be a 5" .357 Magnum. The caveat being that bears or larger dangerous game weren't a realistic possibility. If I was in Alaska, or other Moose/Bear country I'd be inclind to go with a larger caliber.
I don't thin one handgun can fill all the roles that we ask a handgun to perform, but some come close. The closest, IMO, is the 4" - 6" .357 Magnum. That is just my opinion though, and worth what you paid me for it.
Biker