I'm a fan of a lot of fandoms and I often prefer the smaller ones. There's less fics and discussions but it's easier to keep track of them. I gave up on huge fandoms like Lord of the Rings and Harry Potter except for specific authors and story searches because it was just impossible to feel like I was really a part of it.

In smaller fandoms, I've often found that fans are more dedicated to producing good fics. That's a generalization, of course, but the amount of crap in larger fandoms can be a big turn-off.