I currently have an old Lennox Elite A/C system that needs to be replaced and is 17 years old! I've have received quotes on both Rheem and Trane. I Think they are both good units based on the information I found on here! I also got a third quote from another contractor who offers Heil and Century. While I have heard of Heil, I don't know much about them or their reputation! I have never heard of Century (also sold as Comfort- Aire) and don't see much info about them on the Internet! The quotes on Heil and Century are substantially lower which raises some concerns! Regardless of brand, I'm more concerned about using a seasoned contractor and knowing that the installation is correct! I think the right installer is well worth any extra cost up front! I'm of the impression the third guy might just be a quick "chop and drop" type of operator, but can't say for sure! Any thoughts would be greatly appreciated! PS The Century/Comfort-Aire have an uncanny resemblance to the Rheem "Value Series" units, but don't know if they're the same or not!