Messi has won the last four Ballons d'Or and 21 trophies during his Camp Nou career, but has not claimed any major international trophies unlike his former Albiceleste boss.
However, when asked by a fan who is the stronger player, the former Inter and Chelsea attacker did not hesitate in opting for Messi.
"I grew up with Diego, for me he was my idol, but I also played with Messi [with Argentina]," Crespo, 38, said during Heineken's #sharethesofa live video chat streamed at half-time of Barca's clash on Wednesday with AC Milan on Goal.
"Maradona or Messi? I prefer Messi, but you can never forget history."
Messi opened the scoring in Barca's encounter with the Rossoneri.