I adore the centre design, reminds me of the sort of spacesuit you'd see in classic sci-fi movies and shows.

Thank you. And, you're right in general. Although these are sketches, images of spacesuits from old sci-fi and simply fantastic films came to my mind.

Middle one: no neck articulation but may be necessary in extreme radiation/gravity/atmospheric-pressure environments where there is simply no other way to engineer survivability. Right: Should be appropriate for most space and Goldilocks Zone zero atmospheric conditions (i.e. Mars, the Moon, etc), assuming the materials are reasonably more advanced than ours are IRL.

You are generally right. Although such a spacesuit design would somewhat limit the astronaut in his actions, at the same time it would increase the degree of his protection in adverse conditions. And if you fantasize, then I think the most advanced materials would be used in the basis of the spacesuit, which are much superior to current materials. Ooh)

All this space suits has a disadvantage of non-spherical shape of their helmets wich still needs some additional light filter, which still needs to be hidden on the helmet back side.

You're damn right. I forgot to depict the light filters, alas. But there is a problem with the sphericity of the helmet. The structure of the host's head. The problem will be either in the shape of the muzzle, which may not fit into a spherical helmet, or in the dimensions of the helmet itself.

So, I still like them all)
For my opinion - the first one has the most widest vision zone.
The second one may be the easiest to put on the helmet ant it can to rotate easily on the base joint.
The third one mostly looks like a gas-mask, which tightly fitted to user's head. It may be a problem to make a neck joint to such helmet.

At the expense of the second one, I will say what I thought about the fact that it is unlikely that he will have the opportunity to turn this huge helmet. And at the expense of the third - yes, the neck section of the spacesuit will be a headache for its creators. Although it all depends on the setting of course. If this is pure science fiction, then it is more familiar to us from real life spacesuits of astronauts. If this is ordinary fiction, then artists have more liberties here. Sometimes it comes to the point of absurdity, from the abundance of unnecessary details on spacesuits.

In the second one helmet user can to tilt down own head with long muzzle without need to touch the helmet front glass. Also the joint of the helmet to the suit's neck is wide and can be formed as circle - not an ellipse as other part of the helmet. So it can rotate without ant troubles)
In the last one the inner pressure of the neck zone of the suit still may made any rotation or tilt too hard.