I think Messi is the best. All the talk of comparing players from different eras or not, I mean Cruyff for example is a real favourite of mine but if one could put Messi against any team in the 70's and they wouldn't know what had hit them.
My judgement might not be fair since I've only really seen clips of some of the older guys, but Messi is certainly the best player I've ever seen.
He doesn't have the achivements of Maradona just yet though. Maradona was a god for the Argentina side, while people often complain about Messi for not showing his absolute best in the national team. Messi still has another 3, maybe 4 world cups in him though. If one is to measure this guy by any normal standards then he should be at his peak around the time of Brazil 2014. Heh, just imagine a Brazil - Argentina final, in Brazil...what an absolute landmark that would be.
(200 000 people were at the "final" between Brazil and Uruguay in 1950).