This depends entirely on your needs. The most common type to go with is a central AC system, but this might not be the best choice for everyone. For instance, if you’re living in a small apartment or renting out a room in a larger house, you might want to invest in something that suits you. A portable air conditioner or a window type air conditioner would be your safest bet as they’re much cheaper and you can easily take them with you whenever you decide to move out.