Yes, they all look surprisingly similar. But then again, these are all pretty decent lenses imho
When pixel peeping full res images, the sharpest of them all is Canon 1.4, closely followed by the youngest lens - Elmar-M and Helios 44-2, but none of the others are unacceptably soft, they are all good performers.
There are subtle color differences, but those don't matter much to me, as they are easily adjustable. None of the lenses has very strong color casts or shifts.
Elmar-M has the strongest native contrast, for me it's too much almost. I find it's often the case with this lens, it's insane in harsh sunlight.
There are subtle differences in the way background is rendered. Interesting to note the difference in the oof highlights in the lower left corner. Most of the tested lenses have distorted highlights, while Canon 1.4 and Nikkor-H have round ones. I'm guessing this is the field curvature? Notice how the Nikkor-S has similar look to that of rangefinder lenses.
Canon also has the smoothest rendering of background, if that's your thing. Notice how the green blob on lower left is rendered.
Seems that technically, Canon is the best by modern standards.
Helios takes the prize for bang-for-the-buck
But for some reason my favorite of all is Summitar... It just seems magical compared to others. I guess its unicorn to fairy dust ratio is higher as I can't point out a specific reason for my preference, but to me it stands out. It's not the models expression either, as I have few more shots and in all of them prefer Summitar.