There are quite a few posts which talk about recommended schools.
One good way to know if you're going to get attention on the ground and in the air is to determine how instructors are paid. Being paid by the flying hour or being salaried (i.e. still get paid if they don't fly) could make a difference to their attentiveness while on the ground. The other factor of course is the number of students each instructor has to deal with. Another school I came across had on average 6 students per instructor which is never going to work.
There are of course many other things to look at and the other posts should give you a list of questions you can gather to ask schools when you visit.
These questions and research will be pointless if you limit yourself to the cheapest headline price for an FTO offering an IR.