Id like to purchase a small shop welder. The two I'm comparing are the Hobart stickmate 235 and lincoln 225. I like the variable crank adj on the Hobart vs step adj. I'd like to tig carbon steel /stick and stay under $800 for complete outfit. I can buy the Hobart new for $369 and the lincoln is $479. Option 3 is a used lincoln roundtop older model copper for $500. Which and why?