Re brands, I revert back to Mr. James' book:
"Over the [last] 10 years countless welding companies have been sold or merged with other companies, often forming companies with new names. The same phenomenon is still happening today. Recently, two long-time, well-known welding equipment manufacturers, Miller Electric Manufacturing Company and Hobart Brothers Company, merged under the management of Illinois Tool Works. Also under the same managemetn are PowCon, Oxo, Tri Mark, Corex, and McKay, other long-time companies in the welding business. So it's wise for anyone who wants to stay current in the welding field to visit American Welding Society meetings, visit your local welding trade schools, and attend at least two or three welding trade shows every year."
I'm fortunate to have a shop like Roberts Oxygen, close by. They deal almost exclusively in Miller (some Lincoln, which formerly was Harris), so the brand decision is not much of a decision for me. But I also keep up with the new equipment by calling up the welding instructor at the local Community College -- he gets to try out all the cool new stuff, for free. Finally, where I really, really learned about this stuff -- I was fortunate to have a case that involved an ammonia and methanol facility in Geismar, La. The old timers there weld critical joints on heat-exchange machinery, some of which is firing off at 5,000 degrees (or other super heated temperatures). I just kept at them, picking their brains (for payment in the local currency -- Budweiser) until they showed me how to weld "correctly," and told me what to buy. I have many funny (and true) stories from those experiences -- for another time, I guess.
Anyway, back to TIG versus MIG, I haven't looked at buying stuff in quite some time, but I understand that you can buy a modular TIG add-on that features a capacitor start or, in some products, high-frequency (best) start. That means that if you buy a MIG, you can later use its transformer to power a TIG torch. I've never tried this, but I understand it can be done -- someone correct me here if I'm wrong.
BTW, don't forget about the plasma cutter (cha-ching -- $$$). Isn't spending money, fun?