For me it would have to be the guild board. I have a pretty active guild going and I try to advertise as much as possible. Next might be the avatar board.
I barely go on the board, because all the kids signatures are really annoying, and I can't tell the difference between their signature and actual post most of the time. When I'm on though, I go on BD.
i don't get on neoboards and here's why... just like i have said in other posts and the whole theme of this site kind of represents this: attention to your acct==bad stealthy acct==good TNT looking at your acct==very bad scammers/report happy people/ board moderators are all present in those boards like crazy...esp the "rs and chat" boards because thats where most abers hang out...i recommend not going on boards at all...but esp not "rs and chat boards"
i go on the plot board whenever there is one, if there are no plots going on i just stay away from the neoboards
I spend my time on the AC making fun of stupid people. Or I go on the HC and look for good pets to adopt, as long as they're not asking for stupid applications.
Virtupets or the plot/event boards. My favourite hobby is to badmouth the other teams on the Cup boards during the season
FC. Been going there since I started Neo and the boards were introduced to the site. -shrug- It's gone downhill, though over the years. 'Specially when the GC collapsed.