I'am needing to replace my system at home and have called several local companies for estimates for several different brands. My question is there a big difference between say Trane, Rheem, Carrier or Lennox. I live in Florida were the AC is very important. The current unit is a Rheem 16 year old and is 3.5 ton unit which I think is to small as the living area is just over 2,600 SF. Any help/insight whith one brand better or worth additional cost would be appreciated.