Here are a few of our personal experiences:
The church-based program we used did use of lot of young adult church members teaching. They were nice, but they really knew nothing about early childhood education. Most of the crafts DS brought home had clearly been done by the teachers not the kids. The discipline was spotty and the classrooms chaotic. DS hated it there. I'm not suggesting that this is the norm; I only want to point out the importance of visiting.
DH's job had a YMCA affiliated preschool program that DS adored. All the teachers had early childhood ed degrees or were in training. They paid well and there was very little turn-over. The teachers really got the kids and the discipline was fair and consistant. They actually taught DS how to behave so as not to be bullied (as well as giving appropriate consequences to the bullies). I don't know about all YMCA programs, but ours was fabulous.
You might also look into parent co-op preschools. I know of some that are fabulous and very affordable. Heck, you could even start your own.
Good luck!
