What skins are actually well worth the cost?

I have seen lately a lot of heat regarding exalted skins, sanctum etc. People complaining how Mythic skins are usually scam and not so good, Jinx skin getting lot of hate, new skinlines only good as splash arts but mid ingame without new animations etc.

But let's focus on the opposite, for a moment.

What are some skins, older or newer ones that are actually great for their price?