MIG when the job is steel, the volume is high, and the bead doesn’t need to be a finish surface. MIG is faster than TIG and cleaner than stick on most production work.
TIG when the bead is exposed, the material is thin or stainless, or food contact is involved. Stick when the work is outdoors in wind, the metal is rusty or painted, or the access is awkward and a stable arc matters more than spatter cleanup.