I broke with tradition on my build and went arc. I bought a cheapo inverter welder off the bay of e that goes from nothing up to 200 amps
I did most of the chassis at about 85, the rear uprights and roll bar at about 130 and the 1mm side panels at about 55. The machine does Tig as well as arc, it comes with everything apart from a gas bottle for tig and cost 140 quid delivered. It strikes at high frequency and gives a really nice quality weld, get it right and the slag virtually falls off so chipping after welding is not needed. Might be worth thinking about. I know most people here like mig, I have never tried it so can't give a comparison.
Enoch.