The plot of preventing the end of the world? The concept of visiting different places and time periods? Figures of myth and history interacting with each other? The characters? The fights? The additions to TM lore? The crossovers? CGs and music? Characters just doing stuff? Something I can't think of off the cuff?
Not a poll because then no one would actually post. Not a flamebait thread, expect disagreements but don't make it personal. If you talk about the gacha/game elements then do it in relation to the storytelling.