With their current game directors? Nothing.
In the right hands? Xenogears, the "Mana" series, proper Soul Blazer sequel. Maybe Actraiser if they keep the gameplay improvements from the remake but fire the fuck out of the art team and make qualitiy assets for it.
My #1 most wanted thing from them though is to do a "Turn based Fan" remake of FFVII. Where they take the assets of Final Fantasy 7: Ever Crisis, re-create all of the 3D models and pre-rendered backgrounds like they did in that game, and give us the FULL FF7 classic experience with updated visuals and a remix soundtrack (optional). I would pay $70 US dollars for a non-Nomura'd remake of FF7 with basically everything as it was but nicer models/4k pre-rendered backgrounds.