Having got my Meopta Opemus working as I want it I'd recommend one of these. You can work with 35mm and MF formats, it swivels to project onto the floor or wall. Also it's almost tractor technology so even a technical idiot like myself was able to give it a complete strip-down and rebuild over about 24 hours. I picked up mine at a cost of 12.00 (subtracting all the other darkroom bits I got) plus another 16.00 for a modern transformer.
Tony