A male ballad singer I personally think sings better than Sung Si-kyung

Kim Yeon-woo is an incredible singer who surpasses the "Kim-Na-Park-Lee" tier,
but since he appeared on "I Am a Singer" and developed a comedic image, I feel he is being far too undervalued.
I believe someone of Kim Yeon-woo's caliber is a genius vocalist who wouldn't fall behind even when compared to Lee Seung-chul.
I think he is a tier above Sung Si-kyung, who is highly rated here.