Was lucky enough to see both live a few times. I think Zidane has undoubtedly had more impact on the game than Ronaldinho over a longer period. That said I think Ronaldinho's best couple of seasons were unbelievable and in those seasons he was probably, though it's a hard call, harder to play against than Zidane. In answer to the OP I think Barca now probably aren't the best team I've seen - I think, as others have said, that Saachi's (maybe even Capello's) Milan may have been more ruthless. But van Gaals Ajax are the only team I've ever seen move it as well.