I've tried Shingen+Micheal+Metatron when I was leveling her and it was pretty fun during burst hours. Makes me wish Micheal's awakening was earlier. Not sure how much changes with Shingen's weapons though.
Morgan I honestly feel falls low on the list. Maybe a with SSR Cybele and double/triple attack team but that'd probably be suited for a Shingen build too, which is probably stronger.