Barca take on Napoli, where Maradona spent a significant portion of his playing career, in the UEFA Champions League last 16 on Tuesday.
Per Goal's Sean Wilson, Pique said of the two Argentinian legends:
"Maradona was a unique player in the history of football, he went through Barca and Napoli, he will be remembered forever.
"But if you ask me to choose between Leo or Diego, I would say Messi because of his consistency and the magic he produces on a daily basis."
Per Dejan Kalinic of the same outlet, when asked if Messi might sign for Napoli one day, he added:
"You can never say never in football, but I guess that is complicated.
"You should ask him as he decides his future. I would like him to retire with us. I can't tell you more."
Messi has long been compared with Maradona since he burst onto the scene as a teenager at Barcelona in 2004.
Football writer Carlo Garganese disagreed with Pique choosing the former over the latter:
Carlo Garganese @carlogarganese
Pique is wrong...Messi is the greatest one-club player in history. Maradona is the greatest player in history. It's that simple. Can't be the GOAT with Messi's performances at major international tournaments. And no, there are no excuses after 15 years #NAPBAR https://t.co/HO1M8OnGcu
Argentinian football expert Roy Nemer favours Messi:
Until Messi and Cristiano Ronaldo came along, Maradona was the most enduring rival to Brazil legend Pele's claim as the best player in history.
The playmaker scored 45 goals in 75 games for Barcelona, helping them win the Copa del Rey, the League Cup and the Spanish Super Cup during his two seasons at the Camp Nou.
He led the Partenopei to the Serie A title in 1986-87 and 1989-90, the only Scudetto in the club's history, as well as the Coppa Italia and the UEFA Cup.
Maradona was Napoli's record goalscorer with 115 in 259 games, until he was overtaken by Marek Hamsik in December 2017. Dries Mertens became the second player to surpass his total in October last year.
His crowning achievement as a player was at the 1986 FIFA World Cup, where he captained Argentina to their second success in the competition.
International glory has eluded Messi outside of a gold medal at the 2008 Beijing Olympics. He helped La Albiceleste reach the 2014 World Cup final and the final of the Copa America in 2007, 2015 and 2016, but they lost on each occasion.
He is Argentina's record goalscorer, though, with 70 goals in 138 games for his country. Maradona has 34 goals for Argentina in 90 appearances.
Messi's longevity at the pinnacle of the sport is virtually unrivalled outside of Ronaldo.
The 32-year-old is arguably the greatest goalscorer and playmaker in the game's history:
He has achieved those totals in 853 matches for club and country. On Saturday, he netted his 54th career hat-trick in a four-goal haul against Eibar:
Since the 2009-10 season, his lowest goal tally is 41 in all competitions. This season he has 23 in 28 matches as well as 16 assists, having missed the start of the campaign through injury.
A sensational move to Napoli late in his career seems highly unlikely, though. Messi's career has invited enough comparisons with Maradona's; joining the club he is most associated with would only increase that.
What's more, despite being regulars in the Champions League in recent years, Napoli aren't among the select group of sides with the resources to pull off such a move.
Messi stated earlier this season his intention to retire at the Camp Nou, so Pique should get his wish.