I don't live in Singapore, so I can't give you advice on what school to look for, but I can give you advice on what to look for from lessons.
The schools are only as good as the tutors who work there. Bad tutors = bad school, since the schools are no more than the actual tuition provided.
All the bright lights, flashy rooms, amazing website etc in the world doesn't cover up bad tuition, or if it does, it only covers it up for a while, as you'll soon realise, through how much you are learning (and if you are learning at all) whether the school is any good or not.
Why go to a school? Why not just find a private tutor who does the style you are looking for? You should create a post somewhere asking for advice from people who have studied pop piano on which schools/tutors they would recommend, and why.
I'd personally try to get lessons one-to-one.
Group lessons are only good for the companies, in that it makes them lots of money.
I've taught both ways, and individual lessons are always best.
Even if you only had an individual lesson once a fortnight, it would probably be better than group lessons twice a week.
Then again, some people are motivated by having others around them, so it all depends on the individual.
If I had the choice of a great teacher, in a stuffy apartment, on an old, bashed up piano, or an average teacher, in a brand new building, with the best of facilities, i'd go with the great teacher in the stuffy apartment anyday.
I really do wish I was there in Singapore teaching at the moment, since there is so much that could be done with the tuition there! There also seems to be a real want to learn pop piano properly, which is great.
So much talent, and all it needs to help it is some direction and guidance by good tutors!