Don,

In a wire welder, a 25-135 amp unit will weld 3/16" steel - but that's pretty much the top of its range. A 30-175 would handle just about anything you want to do in the shop.

I prefer TIG myself, but then I've used one of those for quite a few years. A TIG and a torch do most anything I want. TIG is slower, but I can see what I'm doing much better than with a wire.