Top 5 Hardest champions in League?

Just out of curiosity, who are your top 5 hardest champions in League? Almost every champion in League is incredibly easy to play at a decent level, but I'm talking about who is legitimately hard to learn all their mechanics and secrets about them?

Im going to say: (I understand Lee Sin is difficult to play at very high level but my personal list is capped at 5, because 6 is an awkward number for a list)

I've seen a few of these posts and I actually see a lot of people say Syndra, opinions?