I've gone through the same decision ordeal a couple of years ago. I even had the same two cameras. I still have the Canon. I started with a black Jupiter-8. It's a great lens for the money ($50). My only gripe with it was the sliding aperture ring. Later I bought a Canon 50mm/1.8 ($150) which I still have and use regularly. For a 35mm lens I bought a used Voigtlander 35mm/2.5 Color Skopar ($200), a great performer. I still think I made the right choices then.
+1. I, too, had a Canon P and Bessa R, still have the Canon P, bought and regularly use a Canon 50/1.8, bought and sold a CV Skopar 35/2.5, regretted selling it, and later bought the M-Mount version. I've since purchased a bunch of different LTM lenses, tried 'em out, sold the ones I didn't like and kept the ones I did.
But it's hard to answer your question w/out knowing more about what characteristics you're looking for in a lens. Are you shooting mainly color film, or b&w? Do you want a lens that's contrasty and sharp across the plain of focus wide open? Or do you want a lens that will give you a softer, dreamier look, often seen in photos from the 1930s or '40s? How close a focus do you need? Do you like shallow depth of field shots, or prefer to have everything pretty much in focus? Even among LTM lenses, it's horses for courses. I don't think there's any overall consensus on "the" best, or best value, lens in a particular focal length. If there were, there wouldn't be three quarters of the threads on RFF!
😀
I'm doing much more b&w photography today than I did several years ago, and I find that I generally don't need really fast lenses to photograph the subjects that interest me. So I've found, among LTM lenses, that the CV Skopar lenses represent incredible value for money. YMMV.
You don't need to spend a bundle to get outstanding glass, particularly among LTM threadmount lenses.
