SEER ratings are an excellent guide and starting point. 13-24 is the standard range. AC units with a higher rating are more efficient. Shopping for the right new air conditioner or replacement model doesn't have to be a daunting challenge. First, figure out your budget and need when it comes to cooling. You'll also want to think about the value of your home, as installing a costly HVAC system in a small country house may not make sense. Take your time and weigh your options, comparing units that could work for your space. Before long you'll narrow down your choice of top picks so you can find the perfect AC unit for your budget.