When it comes to Kpop music, I think Zico is the best, the ones you mentioned are really good too, and I voted for Rap Mon because I personally like his style and voice more :)
Obviously Tablo and Mithra (from Epik High) are really good, I just don't consider them as part of kpop.
I could list a lot of cool rappers I know, but I think it's better if I end it here lol

Yongguk and Zelo ! ^^

Yongguk

Tablo, Mithra Jin, Zico and Park Kyung~ Mir is cool too!

Zico, Rap Monster, SUGA, Yano, Kidoh, Taewoon, Mino and few others.

I love Tablo.

RapMon and Zico definitely ^_^
SUGA too, and I would also choose Yano.

They have this raw style that I really love :D

zico chanyeol and key ^^

Mir