Use the formats for their strengths:
35mm: Good for wide and long lenses, and macro work. Portability (if you leave some of the lenses behind!) is good.
MF: Can be very portable (one often has a fixed lens or fewer choices), reasonably economic, and good all-round quality. Practically every design variant you can imagine.
5x4 and up Movements, odd lenses, contact prints, smaller final enlargement.