Shadowverse

Cynthia is the worst card in the poll.

More like the most annoying. Not only in appearance (I still think she looks more like a passive gay boy than a girl), but also in terms of abilities. Not only does she slow down the game with her Kimasou, but she's just generally irritating. Especially when you take her out with some monster or spell, and the opponent immediately summons another one. She's just unpleasant, to put it mildly.
The other participants don't evoke such disgust.

Added 6 minutes later
In the expansion, dragons and sorcerers have been significantly strengthened. It's nice to lose to a sorceress not because of Dimension Shift/Conjuring Force. Although the new legendary is a bit overpowered, especially if the player has 1-2 cards in hand and then summons her. It introduces some imbalance, but it didn't prevent me from winning against the opponent.
An interesting legendary for Heaven, I really liked it, it opens up amulets nicely. But the other Heaven spells don't appeal to me much. I feel like the new amulet and frog were created to please Elanodrochers. The bunny is decent in terms of mechanics, but it's expensive, and by the time you get to it, it's already late. But that didn't stop me from crafting two and using them to win against Runecraft.
Sword has a good legendary, but it's too expensive (if you use it to its full potential), so it doesn't create a strong imbalance.
I haven't had a chance to see the other legendaries in battle yet. I have an undead legendary, but I don't really like Shadowcraft.