Smaller schools
I definitely think that the smaller operators give the best quality. Having been a Chief Pilot at a small (4 plane) "bush" op (so yes I am a little biased) we trained every student as if they were going to be flying into the same short, rough and hairy remote strips in the same indistinguishable terrain as we did on charter. The students all enjoyed the experience, which is a world removed from a 1000m grass/gravel level, no obstacle "ALA" that you will get from the sausage factories. I did my training partly at a small bush school, and spent way too much money being stuffed around at one of the sausage factories. When I see my old bush instructors today, they still remember me, but the instructors from the sausage factories have no idea. I was just a number! finishing my CPL and doing my FIR with a small school, I got serious one on one instructing, not just "next please".
Also as an employee at these sort of operators, I have learnt that you will definitely get appreciated more than if you are 1 of 20 junior instructors.