Point of understanding: There is often no good reason to pay more for certain HVAC systems or components. They do not usually last any longer or provide big benefits exceeding the higher cost.
There are 2 stage furnaces, 2 stage compressors, variable speed blowers, modulating valves, seer ratings from 14-26. AND Lots of "bells and whistles" to choose from.
Note: just a few manufacturers make most of the brands.
Note: ALL brands use many of the same internal components.
Note: ALL HVAC equipment manufacturer's GUARANTEES are materially the same.
Below are direct links to each brands page for: air conditioners, gas furnaces, heat pumps and thermostats.