A good-looking unit with a thin parts supply turns a simple repair into a long wait. Before you compare features, check the parts route. It is the part of the decision that shows up years after the purchase.
Start with the model number
Write down the model number and serial from the nameplate. Those two numbers are the handle for everything else: the parts list, the manual, the warranty paper, and the supplier's catalog. If you cannot find the model on the manufacturer's public parts list, that is the first question to ask.
Ask whether the common parts are standard
Common failing parts on most systems include the motor, the control board, the igniter or sensor, and the capacitor on the outdoor unit. For each one, ask whether the part is standard across models or unique to this one. A standard part is easier to source from more than one supplier. A unique part can take longer to arrive.
Ask how long the parts stay in stock
Ask the installer or the distributor how long this model has been in production and whether its parts are still in the supply chain. Ask what happens when a part is discontinued. Some suppliers keep a substitute kit or an adapter. Others do not. Get the answer in plain words, and write down who gave it.
Check the local route
Find out whether a local supplier can order the part, how long the order usually takes, and whether a technician who knows the model works nearby. A part on a national list is less useful if no one in your area can install it. Judge the route as well as the part.
Where to look next
For the typical service life of the systems you are comparing, read the appliance ranking and the system pages. The ranking is a list of systems, not a list of brands, and the parts questions above apply to any model you consider.