They are all about the same. Carrier, Trane, Heil, Ruud, Rheem, Bryant, American Standard. As others have said Carrier and Bryant are, or where last I checked owned by the same company and have similar components. Trane and American Standard were at one time own by the same but I am not sure they are still associated with each other. Ruud and Rheem are the same product with a different label on them.
My suggestion is to find a dealer who you can trust and will give you good service if needed. Then purchase a mid level product from whoever you purchase it from, and I would also suggest purchasing the minimum SEER rating, or very close to it, that will meet the state building codes. Your dealer will know what the code requirements are and greatly exceeding them in your purchase will give you diminishing returns.
