I have a handful of cheap watches in a drawer, but they never see the light of day so I don’t count them.
For me, the ideal number is three. A quality watch that can be worn everyday without worry, a pure dress watch, and something ‘special’ which for me would be a small, gold annual or perpetual calendar without a moonphase.
If I could have just one, it would be a 37mm Grand Seiko quartz. I don’t know if that’s the most, or least, WIS option there is....