Mito, easily.
Sora has blue blood but that's about it. Mito was the first popular live 2D vtuber and popularized it away from the short form content method. Streaming live 2D is by far the most famous representation of a vtuber. All Sora has is to be the longest living idol vtuber, the legacy of Hololive, and probably the only person of the 4 heavenly kings era to average 5k viewers in 2024. Mito hasn't really done anything of note since that game she created in 2021 to help pick the Niji vtuber you're gonna like.
Mito has less subs but averages more viewers based on way less streaming hours. Miro has never been ticked into giving handjob countdowns during ASMR like Sora.
