Built well, they both will be fine.
Metal rusts, Wood rots. So really as far as durability goes, it depends on drainage and climate.
Insulation - wood is hands down winner.
Consistant quality - metal studs will almost never show up warp and twisted. Wood will depend on locality and what the yard carries.
Fire resistance: Heavy timbers hold their strength longer, but steel won't support a fire. Either way, build in fireblocks.
Wiring: Must use BX, MC, AC with metal studs. I don't know that's a disadvantage except damp climates where steel cladding can rust.
Alterations and modifications. I think wood frame lends itself to adding shelves, windows, hooks, etc. more easily than metal.
Roof and exterior: If you don't mind how loud metal roof can be in the rain, they are pretty low maint. and fire proof. Three tab asphalt is reasobablly long lasting in most places and cheap. Siding, I generally like wood, but depends on fire danger. Plastic is worthless IMO. Real alum siding might be an option, or brick or brick face.
That's my two cents.