For me, I think Science is currently the best class, with very few exceptions (Hercules being one). You have Titania who can take no damage for a period of time and can end fights in 40 seconds or less, Silk, who is one of the best attackers and can end fights in around the same time, Hulk who can stun cheese most defenders, Torch, the best mystic and energy matchup slayer, and so many more.
Watch this video here and answer the question, is Science too unbalanced? If so, what's the solution? Ex: Nerfing these top tier science champs, or releasing new defenders that hard counter them?
https://www.youtube.com/watch?v=qXnsJaHKi2A