If the talk is about Football, there are always competitions. Maradona-Pele, Puskas-Sanchez and many other pairs are compared from the edge of the time. Similarly the cold rivalry stands between two players and they are Messi-Ronaldo.
The main reason they are being talked about is because both of them play at La Liga , both of them are in great form and both of them are associated with a long term rivalry as Cristiano scores for Real Madrid while Lionel does for Barcelona. This is the time when both of them lie in top of the scoring chart. Sometimes Messi shows his power while other time Cristiano spreads his magic. Ronaldo lies at the top of the scorers chart at the La Liga with 30 goals while Messi is 2 goals behind with 30. They both seems to be in the peek of the form at the same time. Being great stars and making some remarkable goals leads to an indirect rivalry.
Not only their performance, but talks in some social Media shows how comparative they are. Some talk about the Portuguese while other support Argentine . The major of Facebook walls and Fan Page about Football leads to talk about them.
However Messi with four European cup with Barca has quite an advantage as Ronaldo has just experienced one cup with Red Devils. Despite Ronaldo has lead his team to first of the La Liga table as they are 10 clear points above the Catalans in the table.
No Doubt both of them stand high in their heels, both are at the stronger side and more or less, both are equal preforming. If one follows in certain title, he is leading in the other. They are almost identical in their form and performance.
So its upto you who do you support and think lies high.