Many will disagree but the answer is Zinedine Zidane. Influence on the pitch cannot be measured by low-level statistics, which most of football journalists use. Messi doesn't even come close to that - if players around him struggle, he's automatically half the player. Ronaldo almost disappears. Zidane had the ability to actually make players around him appear times better than they actually are, without forcing them to sacrifice their own game for him. This is exactly what Messi are Ronaldo are doing to their teams.