Sakuya is the only character that allows you to mill the other player to death. Characters like Suika and Rin allow you to mill yourself for various positive effects.
Al, try fooling around with other decks then. Aya is pretty good, in that you can hit the enemy and they can't hit you. This allows you to deal damage, get bonus damage for not being hit, and then they have to reactivate their beefy spell again later (giving you an SP lead since your spell stays out). However, she has to be able to outlast the opponent (her damage isn't very high), and against some decks it'd be difficult to do that. Kind of a trade off.
You could try instead playing Flan or Remi, who have much higher damage output and both still have a number of ways to easily evade spells. Flan especially would RAPE a yakumo clan deck, as one of her cards allows you to simultaneously burn the opponent for a lot and force them to sac a support on their field. It's very advantageous against anyone who relies on supports heavily (Alice, Prismrivers, Yakumo clan, etc).