Tig is the way to go if your fussy with the welds and you want a nice look and strength. Tig welding is very slow, and difficult in tight spots. If you don't have the time or patiance (spelling), A mig will be much faster and if your talented can look almost like a tig weld. I would never weld a cage with an arc welder. Ugly welds and messy. I'v seen some cars with arc welded cages. I'm suprised they pass certifacation. As for resale, i wouldn't buy it or trust it.