If it’s 1980’s unit heaters look into fixing them if someone hasn’t, get on a ladder at the front of the unit, inspect the heat exchangers for cracks.
They’re simple tech with generic parts so the bill to repair them isn’t bad.
I have a preference for tube heaters because 1.-they’re a radiant heat
2.-the heads can be removed and cleaned easily if it’s a dusty/ dirty environment
3.-they’re usually cheaper to install/ repair then unit heaters
And at 12’ ceiling it should be enough headroom, you just can’t park something 10’ high underneath it.
But both do the job well, I work in a lot of auto shops, body shops and machine shops so I’ve seen enough of them.