Let me start that I do NOT know any of the instructors. Here is my opinion based on the websites:
1) Something I don't like at all about this one... I couldn't find instructors names (to look them up), some pics there just don't look quite right to me, and some descriptions sound kinda "wacko".
2) & 3) I liked them both. Trainer's name is there, you can google it up and lots of links come up, etc...
My instructor is similar to the 3rd one (she's also silver/bronze USDF winner), and she's absolutely awesome. Also 2) seems to be more into eventing than dressage, while 3) is dressage only (from my understanding).
In short, I'd try 3) first, if you don't like her - go with 2), and I'd unlikely to go in 1).