hello nivy,
Delta connection and ATP are both big schools and, I'm sure, have good organizations. I recall though that I heard when I was training in Florida that ATP-trained pilots were over represented in accidents. I think that there were three fatal accidents including ATP-trained pilots within a short while. The Continental-feeder crashing in Boston being the most recognized. I could add another school to your category of brand name schools in Florida, and that is FlightSafety in Vero Beach and also recommend the school I choose which is Paris Air, also in Vero. Paris is small, but really well kept, with so dedicated instructors and well stunning maintenance. You will save a couple of months of training and maybe 30 % of your budget by choosing a school like Paris Air. I have tons of friends who are very happy with FlightSafety too and who really do appriciate the brand name, but fact is that they are still there after I finnished and they will end up spending lots more!