I went with a Viair system for one simple fact. The compressor needs electricity to run. Not motive energy from the engine.
If my rig has no motor, and I need to use air tools, then chances are pretty darn good my battery will run the compressor for a while.
I built my system around survivability. My air compressor is not dependent on my motor, which is dependent on many, many things working correctly.
Besides, being all in for the 3rd party tank, Viair 450, and a hookup kit, I'm still shy of $500.
Besides, I like my air conditioning, and the fact that it works. I like the fact that I don't have to buy bracketry, clutchery, and beltery. I could fab the brackets. But for the time/energy that would take, I could fab bracketry for my compressor, tank, and run tubing front and rear for quick-connects. Plus relocate the air pumps for my diffs, or run them off the main air system, and use propane pressure regulatorss for my lockers.
I simply chose the best bang for my buck, the fact that my air system is not dependent on my motor, and something that is clean and simple. I like the york systems, they are slick and powerful. Can't really beat them for output. But they don't work for me.
Thats my two bits.