We highly recommend Accutemp. We had a couple of service calls on our old heat pump which were very satisfactory. When the heat pump died, we bought a new system from them, and installation and a couple of maintenance service calls since have been excellent.
But, we would not buy a Carrier Heat Pump again. Works fine, but the "programmable" thermostat is just too complex, and difficult to understand and program. And the system won't accept non-Carrier replacement thermostats.