Cold weather: Sig P220 stoked with 230gr XTPs or GDs (9 rounds), Sparks VM-2
Warm weather: Glock G19 stoked with DoubleTap 124gr GD +P (16 rounds), Sparks VM-2
Hot weather: S&W 340 stoked with Speer 135gr GD (5 rounds), Kramer Pocket
I think you'll find that a lot or responses are based on what folks already own, e.g. "I already have a Taurus so that's what's best."
My big three has been constant for some time after owning, carrying, and retiring many, many handguns. At the end of the day, though, it's all personal preference!