My old favorite was Ravnica. The mixed-colored theme was great and it had so many playable cards. My new favorite is Shadowmoor and Eventide. With so many hybrid cards, like you can pay W or G, you have tons of useable cards.
I consider myself a limited player so I prefer sealed and draft. I am curious how the Time Spiral block plays in limited since the card pool is so large. What’s your favorite block and why?