I'm still a bit clueless what are the best ultimates to inherit for an ace Seiun?

So what is the actual benefits of getting higher star uma's? I know it's like +10 stats per 3 extra copies. But isn't there something to do with an ultimate upgrade? Uma copies can't be completely worthless when support cards are such whalebait that makes no sense.

>>719850656
See you at the finish line, Torena