You're opening up a real can of worms with this one! Form the threads which I've read about this, Flight training in the states seems to be very competitive and quite a few of the operators seem to be very defensive about what people say about them on Pprune (threatening court action and so on). It does make you wonder why they are so against an open debate.
I learnt over in the states at Ormond Beach about six years ago. They're OK. The accommodation was nice, but it was a bit of a factory (which is fine if you don't mind putting up with that sort of thing) and I have to say I was a bit disconcerted by the way, on one of my flying exams, the examiner took the brakes off, taxied to just outside his office then got out and didn't come back for 30 minutes! This was logged as part of my test - they were 'flying' hours which I was paying for, but it is difficult to see how the instructor could be PIC when he's not even in the aeroplane! I wasn't the only one this happened to. It seemed standard procedure.
I've heard that Naples Air Center in Florida are pretty good. Have a look in this thread 'US IR for UK IMC qualified pilots' in this forum for the comments of others.