Air conditioning is a matured technology, so most of the popular brands work well. Many of them use parts made by the same manufacturers. So, the main considerations are the price, warranty, attractiveness, noise, etc. Some manufacturers offer anywhere from a 10-12 year warranty on all parts while others offer only 1 year. Whatever you decide, the most important consideration is the contractor you use. For your protection, make sure you use a licensed contractor for your installation. A licensed contractor using best refrigerant practices and procedures can save you time and money! You may buy the best system in the world but if it is not properly installed, you will actually be buying nothing but a big headache for years to come.