I think part of the reason there are so many disagreements here is because everyone has a different definition of dribble. In terms of pure dribbling (running with the ball at speed having the ball stay extremely close to the feet without the use of 'skill moves' like the elastico or roulette), beating a man and weaving in and out of defenders while on the run, Messi is infinitely better - he is in the George Best, Diego Maradona league when it comes to that, & Ronaldinho is just one tier below. I don't understand how anyone can dispute this. However, when it comes to beating a man with a specific 'piece' of skill, for lack of a better word, Ronaldinho is the greatest ever. He has no peers. At a stand still at the corner flag, or with himself surrounded, he will do an elastico or hocus pocus & leave the defender(s) pinching themselves, to see if they really just witnessed what they did - Messi, on the other hand, uses no flash or flair when it comes to keeping the ball. Messi will take on an army of men just running past them with his unmatched ability to run with the ball at speed with it so close to his feet, using his feints & body movements to go past them, which for me is what a pure dribble is. Ronaldinho uses his unbelievably, incomprehensibly large, never-ending repertoire of tricks to get out of a tight spot. I've watched hours of footage from players before my time & from today, & I just don't think anyone is within a million miles of him when it comes to that. So unpredictable, so inventive. It's ridiculous.
While Messi is a better player through ruthless effectiveness, consistency, the fact that he turned up in his CL Finals, and better dribbling (pure running at speed with the ball glued to the feet using feints to beat men), Ronaldinho, is the most unique player I have ever seen, & had a style like no other. He was gifted by God with a sheer control of the ball never seen before (greater than Messi's & co), a spontaneity & flair that made the impossible possible, & the unexpected expected. As talented as Messi is, he is also the player he is because of his brilliant making-of-runs, positioning, intelligence & his ability to use his teammates (the Barca system) to full effect, which he himself deserves a lot of credit for. Ronaldinho was so raw & uncut, all about the talent, the smile & the dancing feet. His touch is in a league of it's own.
Messi is the better player of the two, but Ronaldinho is the most talented footballer to have ever played the game - no doubt.