I do love my vintage 50mm ƒ0.95 Canon dreamlens.
The way it makes everything out of focus fade has an almost painterly effect, which I genuinely appreciate.
If you are intrigued but not ready to splurge serious money on a lens like this, look up Helios 40/85mm or Helios 44/58mm.
They can work on most modern mirrorless cameras, but you will frequently have to set the camera to “release without lens” or something similar and, of course, focus manually.
One pointer:
You usually want to shoot these lenses at or close to the maximum aperture.
When you stop them down, the characteristics mostly go away and you might as well use a more modern and sharper lens with autofocus.