The title say it all.

For me, it would be MU. I'm not really active in any other forums.

Edit: Other internet board counts too.

Nulla in mundo pax sincera
"Always go too far, because that's where you'll find the truth." - Albert Camus

I visit MU most frequently when I'm not doing anything between classes, but other than MU I don't hang out on forums. It's usually image message boards like 4chan.

I think most answers will be MU, because:

1. it is hard being active in many forums, and

2. those who don't use Manga Updates frequently/at all would miss/not be able to answer this topic.

[img]http://i43.tinypic.com/351e59t.jpg[/img]

MU is my first Forum
not really a part of any other forums

here
Shenmue Dojo forums - Been part of this one since 2002. Has absolutely every bit of info about Shenmue, ever. And that's not hyperbole.
Megatokyo forums - My favorite forums. Highly fragmented between actual fans of the webcomic, the people who hate the webcomic, and those who don't care about the webcomic. defeated 4chan.

Sarcasm just doesn't work over the internet.

I've been on a few forums since I've been on the Internet.
MU is the only one that I've actually kept on using since I joined, probably because it's not just a forum, which can get pretty boring after a while. I love all the other features of the site. The forum is just a bonus for me to procrastinate and waste time on 🤣

I'm trying to be more active on the MU forums! >.< I usually get active for like couple hours then go back to reading manga. When MangaHut was still around(and before Nination fucked everything up), I was very active on the forums.
I also go to ExtaliaMS Forums, but I usually just go to the selling forum. =.= I play the private server, but DDoS has been a bitch lately.
That's it, I usually don't use forums/web boards.

MU is really the only one I use more than once a month I think. Used to be pretty active on Mangafox.

"I don't hate people, I just feel better when they're not around."

Bum bum be dum bum bum be dum dum

"Don't you fly?"