I've considered the Olympus OM-1 with a copal shutter, the Pentax MX also with a copal shutter, Nikon FM2 with nice butons and the Nikon FA because of Matrix metering. But I will go for the Contax S2b because it looks classy and I dont own it.
Some modifications would have to be made though.
1: The mount would be changed into a Pentax KA mount.
2: An added automatic mode for aperture piority, program and shutterspeed priority support.
3: Revival of Carl Zeiss Jena for Flektogons, Pancolars and Sonnars for budget lens options.
4: Revival of Meyer Optics for cheapskate lens options.