I did ECC and would highly recommend them. That being said, The folks from ECC don't have a bad word to say about any of the other prep courses and just recommend you get prep from whichever course fits you and your schedule. I think it is more of a pick your poison type of deal. ECC comes highly recommended through word of mouth by just about every military guy I have talked to. I have also read a lot of good reviews for aero crew solutions.