Roger, given your opinion on the subject of this thread, which is obviously your right to hold, can I politely invite you to withdraw so that the rest of us can have a bit of fun discussing what, after all, is just a camera lens.
Hold on. That's what I'm saying. It's just a camera lens. Unless you can define 'character', all you're going to get is a lot of people saying "I've got this and like it... I've got this and like it... I've got this and like it."
You may, I fear, have misinterpreted my opinion of this thread. I find it very interesting. My original comment was light-hearted: one person's 'character' is, in the vast majority of cases, another person's 'defect', though there are also lenses where (as matt_mcg2 points out) the 'character' doesn't seem attributable to defects. He gives the example of Planars: among others, I'd add the 38/4.5 Biogon and the 150/6.3 Tessar, though faster Tessars don't have the same 'magic' for me.
I can't quite see why you were so bent out of shape when I pointed out that actually, sharpness is only one of the qualities that give a lens 'character'. Much as I appreciate the politeness with which you made the request, I will equally politely decline to quit the thread, as I am quite intrigued to see where it goes.
For me, the Canon 50/1.2 has the most character of any lens I've used extensively, but I don't regard it all as 'good' character. That's why I gave it to my chum who really, really loved it. The C-Sonnar has lots of character too, and I'm more than happy to put up with the focus shift and (modest) vignetting. The cracked, scratched Summitar is amazingly good with the big 'rat-trap' lens hood, but VERY low-contrast (unusably so unless my back is to the sun) without it. I quite like good 50/2 Jupiters, but I've only ever tried two 50/1.5 FSU lenses, and I didn't like either. The f/2 TTH Anastigmat on the Reid was (in my view) a nicer lens than the contemporary Summicron. And so forth.
But where is this leading you? After all the advice so far, what lens(es) are you thinking of buying? With the further rider, already noted by several, that with very old lenses, sample variation after decades of neglect, bumps, knocks and 'repairs', may be considerable?
I'd add the warning that the Canon 50/1.2 obscures quite a significant portion of the viewfinder on screw-mount Leicas, making an auxiliary finder all but essential. And to answer another of your questions, there really isn't much with which you can compare the finder of pre-IIIg screw-mount Leicas, except other miserably squinty uncoated finders of the 1950s and before. They're usable, but if you're at all accustomed to anything better, they're something you put up with in return for the other sterling qualities of screw-mount Leicas (or Retinas, for that matter), rather than a reason to buy the camera.
In fact, have you considered a Retina IIa? If you want to stick only with 50mm, that may be a better choice than a Leica in some ways: even more compact, gorgeous f/2 Heligon or Xenon, combined range/view finder. And cheaper, though arguably slightly less reliable and slightly harder to repair.
Cheers,
R.
