My, my, you are asking a big question herehere are some to start out.
- Carl Zeiss Jena Tessar 50/2.8 (Soap bubble bokeh and three element goodness.)
- Auto Chinon 55/1.7 (beautiful, smooth and perfect bokeh You have never seen anything like it. They are quite rare, however.)
- Meyer Optik Görlitz Primoplan 50/1.9 (Beautiful micro contrast and very smooth gradations. Brilliant black and white lens.)
- Meyer Optik Görlitz Primotar 50/3.5 ( four element goodness. So, essentially, most of the organic qualities of the Jena Tessar, but with the more organic components toned down. Microcontrast suffers a wee bit under the additional element, but not too much.)
- Meyer Optik Görlitz Telemegor 180/5.5 (The long telephoto portrait lens. Enough said.)
- Super-Takumar 135/3.5 ( If you check online and find this lens for maybe 30 to 50 quid, you'll think you're insane and you made a mistake and you accidentally bought a way more expensive lens. The micro contrast and resolution of this lens is unreal, especially considering the price.)
- Nikkor 28-85 mm f/3.5-4.5 AF ( You can buy them dirt cheap for less than 100 quid online, and it is a good competent zoom. It even has a macro switch, so if you're just starting out and want to spend little money, this lens is your go-to.)
All of these lenses should be readily available on eBay. I excluded the rare stuff.
Edit: And there's much more. I still have a very limited experience with that. I have some more than I outlined. But believe me, there's some great stuff out there waiting to be discovered. I also fixed a spelling mistake
While I agree with you that my claim was exaggerated, my claim remains true. While the differences you have outlined are correct, the differences for the photographer are basically negligible because it means essentially three things:
Well, before computers, all lenses were calculated using geometric optics, and these lessons are still true. The computer just makes it faster.
And on the topic of coatings, yes, we have gained fluoride element lenses, but what about thorium oxide doted lenses? Yes, you can't use them on digital cameras because the radiation dosage will kill the sensor eventually, but if you have ever seen the image output of a thorium oxide lens, you know what I'm talking about.
Also additionally on the topic of them being bad, alright I'm getting the rare stuff out.
And there are many more where that came from. Old stuff is useful. I'd genuinely like to see a modern post-2000 lens that has optical performance anywhere close to the outlined 3 lenses. Resolution isn't everything, there are more qualities to a photographic lens. We are artists, not computers, needing the highest resolution lens for machine vision tasks. And I do enjoy more organic lenses, like three-element lenses. Yes, the resolution is rubbish, but everything else is great. The colour reproduction is insanely good, as is the micro-contrast, together with its brilliant, out-of-focus rendering. These are just qualities that you cannot get with an 11 element prime lens where every small bit of spherical aberration or transverse chromatic aberration has been tuned out because in the end you add more elements and kill some of the signal. That's the natural trade-off and computers cannot fix the fundamental issue of absorption. You cannot buy physics, more elements mean more absorption. This will always remain the same, no matter if it's 100 years ago, or in 1000 years, the laws of physics stay the same.
Tldr: If you only take away one thing, then just give old lenses a try. There's no harm in trying the cheaper ones.
Edit: And also, yes, lightweight plastics means the lens will be lighter, but you pay the price in durability. And I will always prefer durability.