I did intro flight lessons at ViaAir and Northeast Aviation and later rented from Hortman.
Hortman, at the time, had the largest selection of aircraft and probably still does. It's run by an airline family (a mix of Continental and TWA) and they are all friendly. I'm not sure about ViaAir or NEAv but Hortman also has a 135 operation going with some multi-engine stuff.
If the other two don't have that, you might look into Hortman so that as you progress with your ratings and experience, it is possible for you to start tagging along on some of the 135 flights once in a while when they can let you (such as delivering medical supplies etc.).
This is not a criticism of ViaAir or Northeast Aviation, however. I did intro flights at both but ended up doing zero flight training at PNE for reasons that had nothing to do with the quality of the schools on the field.