I've got three bikes that are my main commuters:

Vintage road bike - fair weather riding. No fenders or racks. This is my preferred bike as it rides so nice.

Hybrid - foul weather bike. Set up with fenders and a rack. For days I expect rain or have to carry larger loads that I don't want to haul in a backpack.

Mountain bike - winter riding. Set up with fenders and a rack. I leave it set up with studded tires year-round and just don't ride it unless there's ice/snow on the ground. I know a lot of people just swap wheels/tires on their regular bike, but frankly I'm not that motivated. Our weather here is very unpredictable and a lot of times I won't decide which bike to ride that day until a few minutes before I leave the house.