No Particular order based on quality of blog, teams, rollover..
Cooperstown- Fast rollovers, Rules, Competitiveness and great commish.
Doubleday- Fast rollovers, great owners,Competitive, Blog is great
Moonlight Graham- Not in this world but it's always talked about and always fills fast.
Moneyball- Another one that people want to join- Competitive and good structure.
Sag's Memorial Ball Park Franks- Very fun world with a great blog and competitive spirit