Ronnie hands down...
You can just see all the highlights in youtube and it's endless... Ronnie's brilliance shining through! At that point in his career he has already won the Balon D'or and FIFA WPTY twice so it was his peak. As that recent article by a journalist/Madrid fan said "stop the Brazilian, and you can only stop Barca" but you can't say the same with Messi 08/09...although of course Messi is vital in this season no doubt about that. Ronnie during that period embodied grace, class and superiority as a footballer... technique, speed, game winning passes as well as goals, free kicks, penalty kicks, corners, header shots, 1-2s, right & left feet shots, one on one (can't recall the team but it was during a CL game when he won a ball among defenders and proceeded to a goal with a venomous shot from outside of his foot! the magnum effect as they would describe it), hat-trick in CL vs. Udinese that time!! And who can forget his performance in Bernabeu in Nov 05 when Madridistas paid homage to him, which is a rare occurence, once in a blue moon standing ovation to the Magician!!!!
Messi is yet to perfect his craft to say the least... but he has a real potential. He has to improve his free kicks, header shot, when doubled/tripled team has to learn to make that decisive pass, and the most important thing is... when to pass to team mates bec. he has the tendency to over dribble at times. His dribbling skills is his greatest assets and his acceleration. To a certain extent he is just like Ronnie, a magician!