That is a great question. Determining the correct air conditioner for your home depends on a number of factors including the size of your home, whether your home has existing ductwork, your energy usage, and the SEER rating of the unit. Buying a unit that is too small or too large will keep you from operating efficiently and can keep your home warmer than you want it to be. For traditional air conditioner installations, the top five brands are: Trane, Amana, Carrier, Lennox, and Rheem. Each brand has its own fans and its own strongpoints.