Ah... Korea. A nation that has a deep connection with me. :D
Syngman Rhee and Park Chung-hee are highly controversial historical figures in Korea, for they indeed had their achievements but also had defects and flaws at the very time. So no offense, but they are hard and unrealistic choices.
If you meant Taejong of Joseon, father of Sejong the Great, by "Taejong the Warrior," he's my favorite Korean king. He was a charismatic and ruthless ruler who purged anyone who dared to question his power(including his own relatives), but he was also a kind and merciful king to commoners. Several interesting stories and episodes about Taejong may be found in Sillok (Annals of the Joseon Dynasty).
Outside of the choices, I also believe king Muyeol and king Munmu of Silla would be good candidates. By successfully establishing an alliance with the Tang dynasty and conquering the kingdom of Baekje, King Muyeol laid the groundwork for Korea's unification. The Silla-Tang army defeated the kingdom of Goguryeo under his son(king Munmu)'s rule, and Silla unified Korea for the first time in history.