I studied at Bunka a really long time ago but studying at Ikoma now
I feel Ikoma is very good for unmotivated or busy learners like me
. I have not done the homework in years but still manage to get through most of the lessons. Bunka on the other hand is overall shorter in total duration and thus more intense.
One of the advantages of Bunka is that they teach you all the forms (including the very important dictionary form) right from the start, In my opinion, this is a very good move as it becomes easier for the student to conjugate the verb in more advanced classes. Ikoma starts from masu-form and then goes back to dictionary form. While not an issue for many students, some students have to first conjugate the masu-form backwards back to dictionary and then conjugate forward again. Bunka is really better for me for elementary class.
In terms of location, Ikoma wins. It is so close to the MRT whereas Bunka is a short walk (unsheltered) from the MRT; the location is a little bit at the fringe of Orchard Road.
Classroom setting wise, I slightly prefer Ikoma where all tables face the front towards the whiteboard. I haven't been to Bunka in awhile so my experience may be outdated, but their seating is U-shaped so most of the time you will be facing your other classmates. This is for the purpose of practising conversation with different people. Downside is that you may have to tilt your body to face the whiteboard.
Physical/online wise, I prefer physical by a large margin (especially if its a weekend class). Can hang out at Orchard Road after class but more importantly, I cannot concentrate when the class is over Zoom. I will do almost anything else (online shopping, reading forums like this etc.) but will not listen to the class. I also don't really like to talk to the screen for Japanese lessons (I'm ok to do this for work though haha).
Sensei-wise, it's really up to the individual but most impt you can find one that you are comfortable with. Some are funny (huge plus for most people), others are more serious but good at teaching, but there are also some that don't really teach well even. Similar to real-life, the more charismatic a sensei is, the more popular with the students.