One of the only things consistent about Crystal (now Eternal...) is that every new iteration has a brand new character designer. Frankly, I don't think the final arc will be any different unless these movies are a huge hit.
I only have one true preference that I feel would be firmly grounded in realism:
Hisashi Kagawa: Not only did was he responsible for the character designs and (some of the best) animation direction for the S and SuperS movies, he still works for Toei and has done design work for anime as recent as Tiger Mask W. And he's constantly drawing Sailor Moon unlike anyone who has worked with the franchise before. But if you thought that was a no-brainer just look at this doujinshi which he released recently:
Literally just take those designs and add all of Crystal's details (Usagi's sideburns, etc.) and you would have the best character designs the series would have seen in ages. Not only are his designs STILL dynamic and fresh, they have the right balance in terms of the age the senshi look, the right level of detail without looking too overly complicated for the other animators to copy.
I only have one true preference that I feel would be firmly grounded in realism:
Hisashi Kagawa: Not only did was he responsible for the character designs and (some of the best) animation direction for the S and SuperS movies, he still works for Toei and has done design work for anime as recent as Tiger Mask W. And he's constantly drawing Sailor Moon unlike anyone who has worked with the franchise before. But if you thought that was a no-brainer just look at this doujinshi which he released recently:
Literally just take those designs and add all of Crystal's details (Usagi's sideburns, etc.) and you would have the best character designs the series would have seen in ages. Not only are his designs STILL dynamic and fresh, they have the right balance in terms of the age the senshi look, the right level of detail without looking too overly complicated for the other animators to copy.