My first tig machine was a thermarc. It was a scratch-start, dc only machine. I later bought a Lincoln square wave 175 for the capability of doing ac aluminum work. I used that machine for a few years, and decided to add the water cooled torch. It just isn’t practical to use the gass cooled torch if you are doing a lot of aluminum work. That machine only gave me trouble once. My area near the welder was also in my grinding area. The grinding dust accumulated in the arc initiating points and caused the machine to start the arc very poorly. Cleaning the points was simple, and brought the machine back to “like new” operation. I would recommend this machine to anyone who needs a versatile home machine. I still use that machine at work for small projects.
My current machine at home is a Lincoln precision tig 275. It is very nice and smooth in operation. It came equipped with a cart with storage, on board cooling system, tig pulser, ac balance control, etc... the one drawback is it takes up a lot of floor space. On the plus side of that argument, none of my friends come over asking to borrow it, because it is not a mobile machine. I picked it up on craigslist for $2500 from a business that was closing.