Recently, I've been reading about fountain pens. You can get some inexpensive ones, and of course they go up to limited edition Leica prices. A lot of the top end pens might be able to lay down a beautiful line of ink, any better than a $500 pen? No. Any better than a $100 pen, possibly. Any better than a $10 pen, probably.
I think the same goes for lenses. The best lenses can likely render a scene "better" than a not-best lens. Noticeably? I thoroughly doubt it.
I had a Summarit f/1.5 a little while ago, really nice lens. Wide open, the technical quality was shocking. Contrast dropped off very noticeably, it became flary and soft. I didn't care because if I wanted sharp I could go down to f/5.6 and it was sharp. Also, it's f/1.5 performance was technically poor, but I kind of liked it.
Now lenses like that in the Leica line up, have character, had that been a FSU lens, then it would be considered crappy.
If you like nice things (I know I do), then keep the lenses, but for technical quality, well, I wouldn't.
Frankly, in film, I think 35mm is great for convenient, small cameras, but if you want quality, you can replace thousands of dollars of Leica gear with a couple hundred dollars of medium format gear and get very noticeably, strikingly, better technical performance.
If technical quality isn't your top goal, then shoot 35mm by all means, but if it it's important, then you can make life easy for yourself by just getting a medium format camera. No bigger than a M6 with lens.