The equipment sets most of the price and performance, and it's often the vaguest part of the quote.
Model numbers for everything
Outdoor unit, coil or air handler, furnace and thermostat. "Heat pump system" or "16 SEER2 AC" could mean very different equipment. With full model numbers you can look up exactly what you're buying.
The AHRI number
The outdoor unit and the coil are rated as a pair. The AHRI certificate shows that pair was tested together, gives its efficiency rating, and is what most rebate programs check.
Equipment tier
Single-stage, two-stage and variable-speed equipment can be thousands of dollars apart, and one brand often sells all three. When you compare quotes, compare the same tier.
Sizing
The size should come from a load calculation for your house: insulation, windows, air leaks and ducts. Copying the old unit's size repeats whatever guess was made last time. The quote should state the size and how it was chosen.
See where your total lands for the system on your quote.
Common questions
What is an AHRI number?
It certifies that an outdoor unit and an indoor coil or air handler, sometimes with the furnace, were tested together. The efficiency rating and most rebates depend on that exact combination.