Elmar-M 50 has best Tessar rendering I ever seen. I had black one and sold it.
It has flimsy feel and was way too long with filter and hood for 2.8 lens.
I don’t know if 50 2.5 has any rendering at all or it’s predecessor Color Skopar 50 2.5.
Best lens for M3, IMO, is collapsible Cron. It is same size with Elmar-M 50, but rendering on BW is just perfect. And better build. None of the later Crons are close to it, they just sterile, next to flat on bw film, prints.