Fire - Brynhildr (would be cool to see her get improved)
Water - Kikure Hime
Wind - SSR Freja (i'd like a version where her heals and buffs are teamwide and not single target, and she's cute also anyway)
Thunder - SR Perun and Cherubim
Light - SSR/SR Kamadeva perhaps? (she'd be great if her debuffs would hit more often) Daphne would also be an option
Dark - (cant think of any)
another one that I would like to be obtainable by players is the thunder rag catastrophe (maybe even the other rags) as an SSR eido right now, since I actually like her art, and because why not? like maybe they'd give an eido effect of 40%elem/20%hp as an improvement over their lame SR versions (which only low rank players would probably use..)
would honestly be cool if they did this and I wouldn't mind if they had a low drop rate (probably the same as those phantom SSR weps from the new ragnaroks at DMM)