It really depends what you wanna focus on.
For Bunka, focus on Intermediate is more on grammar, less on conversation. From Pre-advance onwards, then they start to focus more on conversation.
For Ikoma, it's more well-rounded. Although i have students who are doing in Ikoma as well as my class as they feel lack of conversation practice in Ikoma.
Ask yourself
1) What's the purpose of learning Japanese?
2) Do you hope to speak or write or both?
3) Are you willing to start from beginner or what?
4) How determined are you to master the language?
5) Are you able to allocate 2-3 hours per week to revise your work?
In both Bunka and Ikoma, i have seen numerous good students and bad students. A lot have to depend on yourself.
I have attended quite a number of the schools' lessons, but i must say that Ikoma and Hougang Japanese Language School is quite structured.