Woah. A lot of votes for Li Qiye. Why? lol I think Meng Hao would win. And I'm under the impression that it would be an easy victory for Meng Hao. Li Qiye "knows" while Meng Hao "learns." We see this in the last battle Meng Hao had. He pretty much understood the Dao of his opponent in order to beat him. Every dao path Meng Hao faced be it in pills, animal taming, dao cultivation, etc... he perfected in his life time. From what I can assume Li Qiye lived longer than Meng Hao which is the reason for his omniscience. Also in a battle where plot armor is disregarded, Meng Hao wins.