I compared each LoL champion's winrate across Bronze, Silver, Gold, Platinum and Diamond to see which champions perform relatively better at high elo compared to low elo. This list is the 10 that are most improved with more talented players.
#8 - Olaf
I don't really know much about what gives Olaf a high skill ceiling but I've seen that the pros seem to play him more than people in my rank so that makes enough sense to me.
Here are Olaf's winrates across the board:
Bronze - 45.48
Silver - 47.53
Gold - 49.03
Platinum - 50.82
Diamond - 52.37