Ronaldo below Best?He's 29 and, as far as I understand, leading a healthy existence. I don't think it unreasonable to expect Messi to compete at the highest level for the next five years.
Is he the greatest player ever? Probably.
My favourite great is Zidane, but Messi has probably made a greater impact over his career with Barca. I would say Messi is also better than Pele and Maradona.
Regarding Cristiano Ronaldo, I think history will judge him in the bracket below Cruyff and Best. Ronaldo's recognition in the Messi-era is defined by sympathy for a player of world class ability and gigantic ego who is completely eclipsed by the diminutive Argentinian.