I want to like Lainchan, but something about the posters and or culture there bothers me, and the board I'd be most interested in, their technology board, seems particularly low quality. I will leave for months at a time and then come back hoping things are different, and they aren't. It's not like visiting the hell that is 4chan /g/, but it's not great. （ ´,_ゝ`）
I browse kissu quite a bit. It's not quite my thing in terms of culture, but I do like it anyway. They stream shows a lot there too.
I browse nashikouen but that site is incredibly slow (in terms of users, the software is weirdly fast unlike every other imageboard I've used).
I will occasionally pop into hikari3. It's eh.

I used to go on ProDefCh... rip...
that site was fun, definitely gave me a classic 4/b/ feeling

I'm pretty sure those aren't all the boards I visit, but I do visit them more than anywhere else.

Still, Heyuri takes up the majority of my BBS time and it's not even close. ヽ(´ー｀)ノ
Heyuri numbah one!!!