To be honest, every day is going to be pretty similar, but if I were you, I would go on a tuesday, wednesday or thursday. Even though it is easter, days during the week seem to be slightly less busy. Also, if you book online before you go, you can become eligible for Early Ride on selected rides. This would be a great way to get on as many rides as possible before the gates open for the "on-the-gate" ticket purchasers. This offer can apply to Rita, Oblivion and Duel to name a few. Check out the website for more details. But yes, I would strongly recommend a Wednesday if possible.