Ronaldo can dribble past a whole team and score too, but the fact is Messi is better because he is more of a team player, has better dribbling skills because he gets the job done simply, by not showboating and just beating his man.
Ronaldo is probably the best freekick taker in the world, but Messi is a more consistent performer, and is good in the air even though he's small, but Ronaldo is also good in the air.