For a home welder with off-road projects, you'll want a MIG welder, with shielding gas. The learning curve is shorter and steeper. Get a 220v welder and at least a 175 amp machine. You don't want a TIG machine at all--it's way too slow.
I run a Millermatic 210, the new version of the same machine is the 212. Great machine, and I've not needed more welder. I built an entire SOA 40 with that machine, plus sliders, and lots of little projects. Starting a set of 60 sliders now.
The 251/252 is slightly more adjustable, but in home use, I don't think you can tell the difference in the 210/212 (vs the 251/252) machines. You may as well save the price difference.
Lincoln also makes equivalent welders, and while most here prefer the Millers, if there was a major sale on the Lincolns, that would be enough to tip the balance that way. I was at a friend's house the other day, and he had a brand new Lincoln 215. It is a nice and high quality machine.
Remember, a welder is a "permanent" tool. Once you have one, you will never be without one again. Do not be afraid to part with a few extra $$ for the right machine. It is hard to find used ones, but with the general slide in the building trades right now, it might be a good time to look on Craig's list or a place like that.
I bought my welder from Indiana Oxygen, who is a huge internet seller of welding stuff. They have an ebay store so go there to browse. It was a very good transaction. Avoid any of the Chinese welders. You want a brand with standard consumable parts, as well as widely available repair parts. That pretty much narrows it to Miller, Lincoln, Hobart (Miller's second line brand) and maybe ESAB.