For me - 3 bikes
1. Gravel bike for commuting, fun, & everything else during late spring, summer, & early fall.
2. Cheap Schwinn BSO with fenders, disc brakes, & studded tires for winter weather commuting
3. 29+ mountain bike for dedicated trail riding.
Advantage of multiple bikes - even when one is broken, or getting a tune up, you always have something else to ride.