It is very hard to judge given the different conditions they played. Having watched a lot of Serie A for years, my pick is Maradona, with Ronaldo de Lima a close second. The thing is that in the Serie A the marking is very good, individually and collectively. I saw full video matches of Maradona and was in Italy when Ronaldo played at Inter. Another thing with the Serie A is that players may be forced to play different positions for tactical reasons. I remember Ronaldo sometimes played on the wings to stop some opposing wing back from overlapping, and even Maradona had to deal with that too.
They mark so tightly that sometimes there is no space to turn. Higuan scored 36gosls in Serie A last season, and that had not been done since 1934. That gives an idea of how tough Serie A is to score, when you consider that top players like Sivori, Mazzola, Maradona, van Batern, peak Gulit, Baggio, Ronaldo, Zico and Pkatini played there.
Even now in Italy they laugh when they hear that Messi and Cristiano score 40 goals or more per season.
I also feel that George Best is often excluded but I think he was as good as Pele, Maradona, Ronaldo de Lima and Messi. May be his peak was too short, even shorter than Ronaldo's peak.
For me the discussion would be who is the best between all the guys I mentioned above, not just Pele and Maradona.