Up until a few months ago I had a FM2n with a Zeiss ZF2 50/1.4 and the plain matte screen (I believe it was the B2, got it for $10). It was a fantastic combo, I loved the Zeiss glass and the screen was really good for focusing, no problems with it and always bang on focus anywhere on the frame. I have no experience with the Contax bodies so I can't help you there. If you go down the Nikon route you can save some money by going for the first generation ZF lens (which doesn't have the electronic contacts) instead of the ZF2 which you don't really need for film bodies.