Onatel as tank. She forces a purple stack just like Guin. So just pair her up properly.
Santa is just meh.
Zim is not bad but better for left wing.
Drake is solid but more of a flanker/wing type hero.
The more I play against Victor, the more I find him less useful. Its just me.
Victor is better on offense IMO.
All said, what are you looking for? Defense I assume.
For offense, I strongly suggest Zim. Highly useful in most situations.
And for my latest trolling, I would suggest you give Kashrek a try at tank.