When it comes to which brand I prefer, I do like certain features on certain brands. However, there are wide varieties of equipment types (e.g., air-conditioning, gas heating, electric heating, oil heating, heat pumps, refrigeration, etc.) and no brand is the best all across the line. However, as I often reply to end users, I think that the choice of installing contractors is far more important than equipment brand, because even the best-designed equipment will perform poorly and fail early if it is mis-installed. And believe it or not, that is all too often what happens. Let's consider some of the many mistakes that installing contractors often make. For brevity I will cover just air-conditioning mistakes here.