[hotpotamus]

I don't really follow the used market that much, but I'm thinking the is the best answer if you've got a good budget to work with and the other post saying the Pentax K1000 is better if you don't.

One potential advantage is the ability to use old Nikon lenses on newer digital cameras, but that's of limited utility when trying to use old manual focus lenses on modern bodies that aren't really designed for them.

[frostburg]

The manual lenses are actually better on modern mirrorless cameras than on older dslr ones, because those had viewfinders that made focusing manually rather hard, while the mirrorless bodies have good focus aids.