I looked at the schools in Florida last year. The only one that gave me any impression of being professional was Delta Connections Academy at Sanford.
You have to look at the groundschool as well as the flying side. At Sanford, all the groundschool instructors were English and had all got CAA approval and all had previous experience as instructors in the UK. The groundschool is actually staffed by Atlantic Flight Training from Coventry.
The other plus points for DCA are that they do the visas for you, they have accommodation available, and you can get dirt cheap flights to the UK from from Sanford Airport. They have lots of aircraft and if you are good enough, they will take you on as an instructor to build lots of hours towards the 1500 and pay you.
Unfortunately, I had a business and couldn't afford to be out of the UK for a year so I chose a UK school instead.