To clarify, this is open ended. Whatever you think is crap is fine. But I mean the skins that are old, not flashy, and yet still have a place in your heart.
For me it's Shurima Desert Zilean. This 8 year old gem has it all:
* Slim clock on his back
* Weird floating rock just off of said clock
* Splash Art that makes him look like an Ayatollah
* Bonkers mustache that is unmatched even by Braum
* Rarely used in game meaning people remember you
There will never be another like it.