It is the most dangerous attribute in football for an attacking player, and Messi is up there with anyone to have played the game in this aspect. He can take apart teams by himself with his brilliance, where as attributes such as heading are reliant on the service of the other team members.
People always go "so and so is good at this, but player y is good at this", but it just doesn't work here, especially given how good Messi actually is at running at players. A player who is an excellent dribbler of the footbll isn't just aesthetically pleasing - he's also likely to be the most damaging player on the pitch. Taking on and beating just one player causes havoc amongst even the best defences, nevermind beating 3 or 4 men like Messi does.