I like crystal. I'm talking about the design of it. We have seen a lot of different types of it, different color, different shape. So, what crystal is the most beautiful for you? Me personally, I would say Titan Crystal. But my all-time favorite one is the 4 star crystal.
For reference:

Valiant Crystal

Incursion Crystal

Titan Crystal

7 star Basic Crystal

4 star Hero Crystal

3 star Hero Crystal

PHC