I'm looking at miller's now, but it's a pretty big investment.
I bought my MillerMatic 35 used about 20 years ago...I think it was made in the early 70's, it's never let me down...I see them from time to time on CL/etc in the 400-600 range, if you've a need for more machine, the Miller 200 will treat you well also, priced about the same as an MM 35.
The only welder I ever bought new was a Miller Vintage (for my dad) very similar to the older Miller 200, but you just rotate the handle (instead of changing taps) but it and the spool gun set me back over 2K and tat was 10-12 years ago...had I known my MM35 was such a runner, I'd have bought an older 200 instead of the new Vintage.
I'm sure older/used Lincolns/etc would be just as reliable