I am slightly biased as Cabair are my FTO of choice but I have done a **** lod of impartial research into the major FTO's and Cabair ticked the most boxes for me. But as many others will tell you, its a personal choice on which one suit's you the best. There are a few top notch FTO's in the UK who are in bed with the airlines and CCAT are definitely one of them!
Good luck fella!
CS