I like the Tig better for several reasons. I originally bought it to weld chrome molly steel and it does a much nicer/cleaner weld for that. Ive seen some nice mig welds on aluminum but im not sure how it would do on the thinner stuff. Im pretty sure you need a seperate cable for doing aluminum with mig because the wire tends to gall up feeding thru.
Another thing when welding with the Tig there is no smoke, sparks or splatter. I never was comfortable welding in a shop with balsa wood and saw dust in the cracks and corners with sparks flying everywhere. And if you have ever mig welded you know the sparks and splatter really flies.
Its nice even in the winter I can go in the shop and weld for a while and there is no smoke to clear out.
Adam