I've owned and used commercially nearly all major brands including Miller (primarily) Lincoln and Hobart. Never had any particular downtime with any of them as long as the hired help operators took care of them. I still have a Miller MIG, a Hobart MIG and a Lincoln AC/DC box. All work fine. Just stay away from the HF and import crap.
Incidently both Hobart and Miller have the same owners since 96'. Also owns Smith, Weldcraft and several others in the welding biz. That's the way it is in the modern world. Buy a quality machine, even a used one, and learn to use it correctly and take care of it and it won't matter all that much which flavor you use.
