I think your best bet would be to go and see all three and get a sense of who you feel most comfortable with. There are some basic things to consider.
Never, ever pay up front for flying lessons and beware of schools that suggest it.
Ask them about the learning process and if you get a systematic answer and outline of the course that's a plus.
Consider their attitude, are they people you might like or at least feel reasonably relaxed with.
Look at the aeroplanes, they are likely to be well used but if they are reasonably tidy with all equipment working that's a good sign, lots of "inop" labels not so good.