This is why stats are important as well. If you don't see that Messi has been playing in 1 system his whole career where the team is built exactly for him he obviously will look like a much better player.
But when you notice that he prefers to have the ball in his feet all the time, (or otherwise he won't feel like playing) when you notice that he comes deep to get the ball so often it all affects the perception of how people will see him.
Because Ronaldo has adapted to multiple teams and has played equally well in multiple systems it doesn't look like he's that good as Messi even if his stats are similar but if you look a bit deeper you can see that Ronaldo has had a broader repertoire of football skills overall. So it all comes down to who do you prefer, more variation or more of the same.
I would pick Ronaldo over Messi, not because he knows how to play better than Messi but because he can give much more to a team overall and still put up the numbers, the same argument I can give about Drogba, having him on the pitch brings more than just good numbers, he was a great leader that could hold a team together through the toughest days.