Your choice of welder depends on what you are wanting to weld.
I do alot of thin gauge sheetmetal, rust repair, etc., so I am very happy with my welder. I own a wire-feed Mig 110v. The 110v is great because its handy to run of house current, and the machine is easy to dial down for very light use, so it won't burn through. I can turn it up and weld exhaust, or up to 1/4" frame steel, so it basically is all I need for my van.
If you are doing more fabricating, and building lots of frames, roll cages, etc. I would recommend a 220v machine. But if your primary bag is rust repair and sheetmetal, then a 110v machine is a better choice. I like my little Miller, but I have also used my friend's Hobart Handler 110v unit, and that is a good one too. Either way you go, make sure to budget for a cylinder of shielding gas. You will want that. Stay away from flux-core wire, its more trouble than its worth.