Your gonna hit a nerve here with that question lol. I also debated it in my garage as i do a lot of fab work and mech. work. I went with the smart siding exterior i think its called. Comes in 4x8 pieces and its made to resist rot and is more durable then drywall. Its groved so it goes together nicely and its primed. Paints nicely. Heres a pick of mine with some paint on it, hope it helps