nerdy

Here is my personal checklist.

Obviously correct sizing is important. If you are unsure, then request a load calculation or even perform it yourself for a nominal fee online.

there are three equally important components-quality HVAC, the install by
dealer, and probably the most overlooked and disregarded is the ductwork system.

these are my minimum specs for a new HP system. both outside and inside units should be replaced to have a properly matched system.

15 SEER, 12.5+ EER, 9 HSPF
best matching VS air handler
full BTUs in both cooling and heating for your rated size
R-410a refrigerant(same as Puron)
scroll compressor preferred
electronic demand defrost preferred
thermostat with "dehumidify on demand" feature
staged backup heat strips
new and correctly sized refrigerant line set
10 yr parts warranty/10 yr compressor warranty

you want a thorough inspection of your ductwork system. size, overall condition, supply and return lines, insulation qualities, leak test, etc.

any hot/cold spot issues in your home should be addressed.

I would only use authorized dealers for the various brands that provide quotes.
see mfg websites.

I would look at Trane/AmStd,Rheem/Rudd,Carrier/Bryant.

Depending on your location, I would not purchase a new HP system that did not have electronic demand defrost.

IMO