I've used the Hobart 140. It's a goog machine. It's better suited for sheet metal, 3/16 steel would be about the thickest though.
I bought a Lincoln 180 from Home Depot, I'm glad I went with a 240 Volt unit. It's night and day different(better) than a 120 Volt unit. If you're going to spend the money, I would spend the extra $100 bucks. It's well worth it.