Football has this very wierd differentiation between 'best' and 'greatest'.
'Best' player is fairly self explanatory, in that it is simply who is the most gifted and effective player usually. 'Greatness', however, is made up largely by 'moments' in a career.
Ronaldo (Brasilian) is the best player ever for me, or at least alongside Messi. He is far from being he greatest though, I think perhaps he needed more moments at club level.
Around the time when Zidane was playing, in my view, he never touched Rivaldo's Barcelona level, but his career, at least in the record books, is largely summarised by two headers and a magical swing of his left foot at Hampden.
In 2002, Ronaldo won the Balon D'or. He missed around 6 months of the season I believe, but returned to go to the World Cup, which his team won, and he got the Golden Boot, including scoring in the final. I believe Michel Ballack was second that year. His season involved dragging Bayer Leverkusen, who were fairly unfancied, to the CL final, which they lost to Real Madrid, and then dragging Germany to the World Cup final, although he was suspended for the match itself.
The record books don't recognise his season, which was amongst the best midfield seasons I've seen. The key, crowning moments were missing.
Griezmann has had a similar year. Ronaldo will probably win the Balon D'or this year. He won the CL and Euros. Griezmann came within a whisker of winning both. However, his penalty hit the bar in Lisbon, and he missed a sitter in Paris. Had those moments been different, the story could be very different.
I don't really care for the 'greatest' player. What I do know is that I have very little doubt that Lionel Messi is the best.