Depending on which country I'm in DEC or FEB. The colder the better. If it's too cold even for me, I can always wear more clothes. If it's too hot, and there's no AC where I'm crashing... the lower limit is whatever's acceptable to whomever's putting me up.
Autumn for the temperatures and the vibes. I would also say spring if allergies weren't a thing. But anything but summer, which is easily the worst time of year.
Summer. Warm (I'm anemic and feel cold in low 70s.) Fresh fruits and vegetables are available. I FUCKING HATE Winter. Hate the cold and hate snow. Even if it's warm enough in the cold out makes my arthritis much worse.