>>81638175 (OP)Japanese is the most difficult language, but it's got the biggest learning community, the most resources, and the most content (if you like anime, manga, or light novels) to help you get exposure to the language.
Chinese is slightly easier than Japanese, but all their TV sucks shit and their books aren't much better. It's impressive how consistently terrible it is. You'd think a country of a billion people could make one good TV show.
Korea has k-dramas if you're into those I guess. I don't know much else about Korea. I gotta imagine it's easier than Chinese/Japanese since you don't have to learn hanzi/kanji.
Anyways TV + other content you enjoy is an important thing to look at because 90% of language learning is getting as much exposure to the language as you possibly can day in and day out. You're gonna end up reading lots of books and watching lots of TV.