OK, some numbers, all in px/mm2.
Nikon D610: 28,041
Nikon D800, D810: 41,960
Nikon D7100: 65,466
Nikon D3, D70: 14,009
Nikon D300, D5000: 32,751
(Of those, just looking at the density numbers and ignoring anything else I might happen to know or not know about the cameras, I'd pick the...