Also hard to nominate a player from an era that you personally didn't watch. I vaguely remember watching Maradona in 1990, but I was too young to really know what kind of player he was.
So for me, from my era (90s and beyond), I'd say:
C Ronaldo
Messi
Ronaldo
In that order. The first two are a no-brainer - easily the best two footballer of a generation. Cristiano pips Messi on account of his super-human drive to push himself to be the best, year after year. He's one of the games greatest competitors. Brazilian Ronaldo was also unstoppable on his day, particularly the era from Barcelona to Inter. An absolute monster of a striker.
A special mention for Ronaldinho as well. Probably not quite in the top three during my time, but on his day one of the greatest players ever and an absolute joy to watch.