I need to weld a frame for my solar catamaran project.

To weld now square 30x30 mm galvanized steel. Which one is better to use?
MIG or TIG welder,

I have only experience with MMA ( stick transformer welder) so this new inverter technology is quite new for me, but I just bought new 3 in one TIG, MIG and MMA inverter welder.
Which one give me better result taking into account my limited experience ?