I personally love the "alternative universe" skins

Noxus Poppy, Void Fizz, Underworld (Shadow Isles) Wukong, and now Freljord Taliyah. Those skins that represent how a champion would be if it was from a completely different place from what it is originally. Even when they are not canon, those skins usually allows us to know more of a place. For example, Void Fizz has this Void backgroung which gives you an idea of what the Void looks like, confirming what Vel'Koz said about the Void being a very dark place. Or the Freljord Taliyah. I didn't knew that there were reindeers on Freljord. The background of this skin also gives the idea that some places on Freljord are so cold that they look like real-life Antarctica.

I hope that Riot does more of those alternative universe skins.