Epoxy would be better. Consider if you got mildew again. Odds are you could get it. Even an oil
based enamel finsh can be damaged from mildew.
A one part epoxy paint
I would think would be good enough for non UV applications. In the end, the cost is a bit more but you'll spend a lot of time and money
doing all the prep work cleaning
and priming no matter what paint you use. It would be nice if you got a bit of mildew down the road you could just clean it up and not have to do this again.
home bathroom paints add a anti microbe growth agent to reduce the mildew problem, but it does not last forever nor works perfectly. On a boat it would be a joke.