Ideally you want to put a fan in the ceiling and then duct as straight as you can out of the room. If your joists are running perpendicular to the wall you should be able to find a space that isn’t too bad to go straight out the wall. If you don’t want to cut into the ceiling, or there just isn’t enough space, Broan-Nutone also makes through-wall fans that are about as simple as it gets, this is what I have in my kitchen, and a lot of old homes have.