Wondered why just the two: Engle and Isotherm? The older Engle has a good reputation--sounds like more issues in the most recent units--but based on only a few reviews that is really difficult to judge. The Engle uses a Sawafuji Swing motor--I had the same motor in the two Norcold units which lasted many years. But others have not had as good luck. Part of the issue is power supply--as I remember it is 27 volts AC--so you have to have inverters, converters etc...
The ARB, Isotherm, Waeco/Dometic, all use the Danfoss 35B rotary motor which runs on 12 volt DC directly. The swing motor uses less power at start up--it is more like a car fuel pump--in that the solenoid directly drives the piston for the compressor, rather than rotary converted to lineal forces. On some tests the Engle used less power than others over 24 hours.
The ARB is also highly regarded--and my recollection is that Pat Anderson's used less power than our Dometic.
What is the application--ice for use in ice chest? Ice for drinks, etc? There are a lot of variables so to the best course of action in keeping food/beverages cold.