As usual, I would like to see many things reworked. Perhaps start in small, more manageable chunks. Look at all the Warframes that have not been reworked. Then consider which ones need a rework, either because they don't see enough use across the entire playerbase, or maybe they don't have much utility in endgame content, or are a niche-use case, or you now have the means to make their kit match their theme better. Maybe have the rework launch alongside a deluxe (or 2nd/3rd/X deluxe) skin?