I like Amir, he will teach you until you got it and will never let you off if you are not safe. The aircraft are fine albit not as shiney as Cabair's. As for Firecrest all I can say is that they are good people but as I never flew with them I can't say much more.
Cabair are professional and has large fleet of aircraft, therefore they always have another aircraft to give you if the one that you had to have went tech. smaller schools might send you home even if it is a nice day. Cabair are expensive but it is only you who can decide if you are willing to pay the extra money or not. I never flew with them so I can not attest to the standard of instructing.