If Yugi gets scaling and statement wank he easily goes universal with Holactie and multiversal with Jaiden/Judai Yubel scaling. If Ash gets scaling and statement wank, he receives an extreme highballed universal with several caveats. He also can't summon anything even arguably universal like Yugi can.

If Yugi doesn't get scaling or statements at all, he's easily a citybuster, and probably somewhere around mountain level at full AP. Ash does not go beyond small building level.

It's a simple equation. Yugi wins.