I believe that Messi is the greatest player I have ever seen but to not consider Ronaldo after maybe Messi, Pelé, Maradona would be nonsense.
We can talk about Ronaldo 'el fenomeno' as having more talent, we can talk about Best having more talent but Cristiano has had a much higher peak at the top and that works more in Cristianos favour.
You can't just arbitrarily decide "Well we need to judge it based on what could have been", sadly it doesn't work that way.
Cristiano occupies the #3-5 slot easy, sadly forwards tend to be in those positions even though there's greats like Maldini when we talk about the greatest ever we speak about forwards really.
You can talk about players like Di Stefano or Beckenbauer being "complete" players, Di Stefano: European Cups (5), La Liga titles (8) and .72 goals per game so does he go ahead of Ronaldo it's a difficult choice? the issue is with Di Stefano the Real Madrid side back then was very good, in-fact too good for the league and the European Cup had an easier format, but. He was a big part of the reason why they were so good.
I Just haven't seen enough of Di Stefano to make a comparison since it's so long ago. If you talk about footballing Influence then does Cruyff finish ahead of Ronaldo? from an influence perspective yes, but as a player maybe not.
I think if it wasn't for Messi in this generation people would be lamenting Cristiano as the best in history, but Messi has sadly overshadowed him and makes him look like he's a tier below when he's not.
If you put Cristiano up against someone like Zidané, Cristiano would outshine Zidane although Zidane is a great artist player that sees the game differently, I think Zidane is int he same bracket as Iniesta when you compare the careers both have had.
You may ridicule me but you could potentially say that Ronaldo could come before Maradona (why I say #3-#5) because he's won more, yes Maradona was more talented and what he did in 86 was miraculous but he was only really in comparison with Platini.
Maradona had a .52 GPG ratio, yet never really had as many league titles as he should have done but he made Napoli the team they were, Maradona didn't always make the best choice off the field, if we are talking about peak of players Maradona could be #1 because of 1986 but Ronaldo over his career has proved he was at that level at times and has kept a very high level, for a long time.
I think Ronaldo has achieved more over his career, Maradona what he did at Napoli was amazing but obviously with Maradona you have brighter moments in his career, Ronaldo has won more and maintained a higher level.
You could easily say.
1. Pelé
2. Messi
3. Maradona
4. Ronaldo
5. Di Stefano
But you could easily also say.
1. Messi
2. Pelé
3. Ronaldo
4. Maradona
5. Di Stefano / Cruyff.
It's where you draw the line on talent vs what the player achieved etc.