I don't know, i feel like the VO is pretty lackluster, specially if compared to other VOs.
Kayn just talks all the time about how cool and edgy he is, and Rhaast just talks about killing things, other champions talk about other things besides their main thematic, and I liked that a lot, because you could learn more about them and im a sucker for learning new thing about the characters i like.
For example, through rakan's VO you could learn that he is a pretty laidback guy that likes music, dancing, singing, and in general to have fun. But he also loves Xayah, and even thought he is an airhead, takes their cause seriously (kind off).
The dialogues of recent champions are brilliant, fun and interesting (Jhin, Rakan, Xayah, Kindred and Aurelion comes to mind) why are Kayn's so lackluster?