He is without doubt one of the best im not old enough to have seen the likes of Pele Eusebio Cruyff.
Paulo Maldini is a great of the game but not get mentioned in the same bracket as attackers.
I would say Messi is the best ive seen live and with my own eyes.
One doubt I have with modern players is how would they have reacted in 60-80's where the tackles were brutal, I have no doubt Diego would destroy teams in this era especially with the protection they get now.