I have a pole barn that I had built about 3.5 years ago. It is 24x32 with 10' ceilings. 16' wide overhead door and a walk door. I have fixed windows for light and operational windows as well.
Mine is finished on the inside with the same sheet metal that is on the outside. If I were to do it again, I would use some type of plywood or t1-11 because of the rib joints on the sheet metal. That has made it difficult to hang items on the walls (not impossible). At the time metal was cheaper because of hurricanes driving up the demand on sheet ply.
Insulation is 6 inches in the walls, and 18 inches in the attic. I was out there tonight and it was 58 F in the shop and about 40 F outside. I have no heat source right now but am adding one for this winter.
I would get competitive bids from both types of builders. The great thing about mine is that it was done in about 15 days. (except the concrete poor). I think that is pretty fast considering I mean from site prep to under roof with doors windows and insulation done.
I ran all my powe in conduit outside the walls. Cost a little more but that was a personal preference for me in case I ever want to expand it.
Good luck