If you care to look back at this thread, I've said several times that you can't literally prove that Messi is better than Ronaldo, or vice-versa. It is a matter of personal interpretation and opinion. Equally, someone could state that Neymar is better than both of them, and no-one could literally disprove this.
It is frankly astounding to me that anyone could possibly consider Cristiano Ronaldo to be a better footballer than Lionel Messi, but everyone is entitled to their opinion. However, as time goes by, it's quite obvious that the vast majority of credible and objective judges consider Messi to be better, which isn't surprising as he scores at least as many goals as Ronaldo (his career ratios are better), and scores more difficult goals far more often, while quite obviously being a far superior technical player in every department.
In fact, no-one on this thread has ever really argued against this from the Ronaldo 'side', it's more just feeble arguments about who won what titles and when. No-one can put forward any evidence to show that Ronaldo is a better footballer because it just wouldn't be taken seriously. If he's better at something on the field than Messi it's heading, Messi is better in every other department, including goalscoring and finishing. That's why the Ronaldo 'side' has to resort to silly arguments such as Ronaldo is better in the big games, Ronaldo is more clinical, Ronaldo has a better mentality, Ronaldo won the Euros, Messi has always played for Barcelona.
Any comparison of their actual play and what they have done on the field of play as footballers is never going to reflect well on Ronaldo; indeed, Messi has usually come out on top when they've played against each other. So, obviously, Messi is generally going to be regarded as the better player. But it is a matter of opinion, and anyone has the right to think whatever they choose.