We live in Dallas and are replacing 2 complete units with a 3 ton & 5 ton variable speed. I have received quotes on Trane XL16 & XL19. Also Amana ASX16 and Carrier Infinty 17. The prices vary from $14K to $20K. How do you really compare the various models. I have spent hours on internet trying to compare the units and still as confused as when I started.

Thanks for any suggestions in advance

Word of mouth, reputation, quality of installation and of course warranty are the factors to consider. A brand name is just a name if the support isn't there. Find a trustworthy contractor with references and go from there.