unless you want to do color, go with the focomat -- a lens is easy to find, I use a Nikor enlarging lens on mine, works great, they're cheap. I have a Leitz i could let you have cheap ($50) or I think I've got a Nikon one, too, cheaper. As to filters, you can either put them in front of the lens (Kodak filter sets include a little holder) or buy filters that don't have frames around the edges and set them right on top of the condenser inside the light housing, which is what I do.
the HUGE advantage of the focomat is auto-focus. Once set up you never have to focus again. Never. It is a huge time and hassle saver in the darkroom.