Jiraiya, he had minato, nagato, and naruto and all that those end up doing, as they all(except maybe minato) think about jiraiya and his ways further down the line
Oro and Tsuna kinda tie, as oro and his experiments, as well as what he taught sasuke will always be remembered
While tsuna has sakura, and revolutionizing the “team” system and medics on the battle field... hmm, in that regard maybe it’s more a tie between tsuna and jiraiya for 1st, as tsunades legacy still extends to this day, and isn’t really limited to her pupils but the village itself? I dunno it’s kind a tough one for me tbh