What is the best brand heat and air unit?
A quality installation by a quality contractor will make more of a difference than the best unit haphazardly installed by a lesser quality contractor or DIY. Also I think there is no BEST unit or brand of unit, though there are certainly low end units out there, but that is not the question. Generally speaking all of the units in my opinion which are not in the low end category are good machines and the favorite ones chosen by the better contractors are preferred for many different reasons including simplified and non proprietary controls and other parts, their experience with a particular brand whether it be with reliabilty or warranty issues etc. So I guess I`m trying to say the so called Best Brand is a subjective issue and would depend on who you ask.