They both consider their respective champions to be superior to the other, so that cancels out. Legend may have Valkorion above the Ones, but he also has Palpatine above the Ones, so that doesn't matter either. What's relevant though is that Tempest's Palpatine is a universe buster while Legend conceded Valkorion is inferior to SSG Goku who is also a universe buster.
Tempest's Palpatine wins.