Think what you need this lens for.
There are hardly any bad 85/90mm rf lenses around - it is much easier to make a good tele than a good wide angle. In RF shooting, I have found that I use apertures wider than f 4.0 seldom - the reason is, that when you shoot landscape you want sharpness and textures, and when you shoot a portrait, f4.0 gives you enough dof to cover minor focusing errors. Shooting close portraits wide open has the additional benefit of rouund OOF highlights and smoother shape contours, so an f 4.0 lens is more than appropriate. If you like it biting sharp, go with the Tessar, if you like it sharp but normal, there is an Elmar C 90/4 you can get on the cheap.