ROHM, Japan, Seoul and CREE, the advantages and disadvantages of these LED.

ROHM's is untouched, and Seoul Semiconductor's LED with AC direct drive is an advantage.

The good thing about Riya is that there is no patent trouble, but the price is relatively high, right?

CREE's is good, and the power is good.

PS: It would be better to ask this question to a professional website such as Lighting Technology Forum.