As soon as that Winged Twilight mod came out, I thought of Saya and am so pleased you are thinking of bringing Saya and Kireteki to Skyrim!
I have tried the same modder's summonabe Golden Saints mod and it works well.
Of the four armors you are considering, I think the black plate looks best but, as you say, it is reminiscent of some of your other characters and says Chevalier d'Éon to me. Therefore I find the silver plate to be most compelling of the four. The ordinator armor is very cool as well but I can't get my head around the wider-than-a-door pauldron wings.
That said, I'm afraid I struggle just a bit, as does mALX, thinking of Saya in heavy plate. I know she likes to mace bash up close but perhaps more a combo of steel and magic for defense? What comes to mind is
Ves armor. I imagine the quilted jacket to be internally reinforced with enchanted silk fibers - somewhat similar to modern ballistic soft armor. It is a mod that I use and works well. We don't see Buffy in it often because it does have a bit much steel on it for our tastes. As I said though, it might be perfect for Saya?