It's like comparing Beethoven, Mozart, Vivaldi and such.
Humanly, Messi represents far better the sports value than DM (ok, that was an easy one).
Furthermore, it's tricky to compare two very different periods, just if you consider the finance aspect and also the evolution that led into a société du spectacle in football.
Meanwhile, one is "God" while the other is the -friendly jumpy- "flea" = who wins ?
So, indeed, they represent two different styles but the irony in the perception of this comparison is that Maradona may much more look like an human -and less of a Dios- because of his defects, excesses, scandals while -the- Messi (another oddity in the comparison ;-p) looks way beyond human because of his normality !
Messi is almost divine -un Dios bis !- by his normality : he doesn't crash his Ferraris while coming out at 5am from a night club, he lives a discreete life, when interviewed he looks like a shy kid, not a noise, not a scandal ! It's like if he's living on another planet already.
Also, Maradona holds a very strong symbolical charge : his incredible dribble among three or four opponents -?-+ his magnificent headshot -helped by God's hand ;-p- against the same and symbolical opponent.
And to conclude, look at the YT videos showing the best of Maradona & the best of Zidane (considering Maradona is 5"5 and Zidane is 6"2 = center of gravity...). Is "ZZ" worst than Maradona ? They are on the same level : without them = no World Cup, no European Cup (ZZ side, Napoli period for DM = incredible), no 2006 Final (ZZ came back following a "dream").
Impossible to compare, just enjoy!