Phoenix is a hard place to be a piece of cooling equipment, and it shows up in which Carrier features earn their price here. The city runs roughly 111 days a year at or above 100 degrees, with a normal July high near 106 and a first 100 degree day averaging around May 2. Equipment ages by run hours, not by calendar years, so build quality and serviceability matter more than they would in a mild market.
That also changes the variable capacity conversation. In a climate with a long, flat cooling load, equipment that can run at part capacity for hours rather than cycling hard is doing something real rather than something theoretical. It is still not right for every house, and the honest test is the load calculation and the duct system, not the brochure tier.
Monsoon season, June 15 through September 30 on the National Weather Service calendar, is the other local factor. Dust events pack condenser coils, and a coil that cannot shed heat pushes the compressor harder on the worst afternoons of the year. Coil access and cleaning schedule are worth thinking about at selection time, not after.
Placement finishes the picture. Rooftop packaged equipment on flat roof housing, condensers in narrow side yards and alleys in the older grid neighborhoods, and attic air handlers all change what is practical to install and what is practical to service for the next decade.