I think the first one is the right one
In my head it sounds Kye-on
╮(￣▽￣)╭
But I don't know how it really is supposed to sound
Kye-on
Honestly, I say Ki-On inside my headkui xD but does it matter? I mean you're nit reading it out to class anyway... or at least I hope you aren't xD
Saw the original Korean raws and it’s kee-ohn (long “o”). This is the best phonetic approximation I can offer.
Do you pronounce it like "Kye-on" or "K-yown"?