The original RTS body was Porshe designed. I have owned the 139 and the 167MT and held others including the Aria. Contax cameras are so ergonomic and felt better in my hands than any other SLR camera from the 1980's. Pick your favorite body and go with it.
I owned the German 25 and 180 and the Japanese 35, 50 and 100. All the glass was made in Germany by Zeiss. All my lenses were bought brand new and were all the original lenses before the program mode contact. All were tack sharp and contrasty. Just pick the lens focal length and maximum aperture that you want. They are all great lenses.