Another vote for osb. I have a separate barn that has the rv garage and a separate workshop. In the workshop (heated with a hotdog furnace) I sheeted iy entirely with osb. being the workshop I am always hanging stuff on the walls, don't have to worry where to hang anything. I also primed with Kilz before painting. One thing I did is I put an 1/8" bevel all around the sheets with a router prior to putting the sheets up. This dresses it up a bit especially because you can't get all the joints perfectly flush. The bevel also creates a perfect and easy way to caulk the joints to make it air tight.
Dan