I think few would argue that Messi is a special player. His speed over short distance, agility, and ability to react to his opponent is I think what you are discussing above. He seems to be able to read what the opposition plan to do to get the ball off him, and that generally leads to them being embarrassed by his speed of thought.

Ronaldo is a different player but equally as effective, and though perhaps not as good in tight positions, C. Ronaldo is better in the air and for this reason I would pick him over Messi, just!