Junkyard Trundle for example.
Nothing beats Phantom
for mismatched splash and in game arts. They don't even look remotely similar or share any themes.
Both look terribad.
Blacksmith
seems to be going this path.
It does look like the splash, it just doesn't retain the particular lighting that gives the splash it's character.
looking at you 
Blood Moon
.
Almost bought it because, man, that splash looks awesome. It might be my favorite splash in the game.
Glad I checked out the model before committing, though. Looks more like Cheerleader
to me.
The skin still looks great though.
+1 for gravity falls
and
(penta kill)
I would say Noxus poppy but thats about to change so yay
because a LOT of splash arts have yet to be updated with their champion