What would be a good size equipment bag to get?

I’m shopping around for equipment/duffle bags to use and I see varying sizes ranging from 20 inches up to 32 inches.

Not looking for anything flashy/expensive, probably spending $25 at most.

I’m not sure what exactly to get. I’m not gonna be using it a whole lot. Maybe a few times a month at most, mainly if I’m taking my nephew somewhere. In the winter we might go skating occasionally, so the bag fitting both our skates (or at the very least mine) would be ideal.

In the summer, we might go play baseball (with a smaller kid sized bat). Not sure if a bag is even needed if we’ll just carry the bat/ball with us, or if we’ll wind up playing soccer or roller blading and just having the bag would at least be good for storage purposes.

So what would be a decent size bag to get? Don’t want to get something too small where it won’t fit everything, but not sure if a bigger bag would wind up looking too big, especially if not much is in it (although i would imagine duffle bags wont look too bulky anyways). Price wise I can get any size between 20 and 32 inches for basically the same price anyways, so price isn’t the factor.