I think it depends on your playgroup, so I'll leave this choice up to you
Steel Overseer might just be the best of its type, with a simple but effective activated ability to give your artifact creatures a permanent upgrade every turn
Yuna is a powerhouse that buffs all of your enchantment creatures with useful perks, dealing overkill damage to the enemy player with trample while regaining life for each damage dealt with lifelink
After the subgame ends, each player shuffles their cards from the subgame to re-form their main-game library (and Attraction deck, if applicable), and they return to the main game from the point they left off, with Tug of War finishing resolving and the winner of the subgame getting their reward
Her efforts bear little fruit, however, and suspicion follows her now as her circle grows smaller and smaller
Ardyn, the Usurper Ardyn costs a ton of mana, and while is full of powerful demonic lord abilities, it takes a lot to get going