Dario Nardella, who replaced Renzi when the premier moved to Rome last year, scored 65.0 on the governance poll by Il Sole 24 Ore.
The Democratic Party (PD) politician appears so adored by Florentines that he has jumped 5.84 points on the scale since his election.
Nardella was closely followed by Antonio Decaro, the PD mayor of Bari in southern Italy. Decaro scored 64.0 in the Il Sole poll, dropping 1.40 points since his election in 2014.
In third place came the mayor of northern Bergamo, the PD’s Giorgio Gori, who has jumped an impressive 9.50 points since last year to reach 63.0.
At the opposite end of the scale sat Maria Rita Rossa, also from the PD party, who was voted in as mayor of north-eastern Alessandria in 2012.
Her popularity has plummeted 23.97 points since election day, putting her at 44.0 points. She shares last place with Peppino Vallone, Crotone mayor, and Vito Damiano from Trapani.
The mayor of Rome has also suffered a drop in popular support, coming 82nd place in the Il Sole poll. In just two years since his election, the PD’s Ignazio Marino has lost 14.40 points and now has a score of just 49.5.
Milan’s mayor, Giuliano Pisapia, has fared slightly better since his election in 2011 as an independent candidate. He currently sits at 67th place, having fallen 4.10 points to 51.0 in four years.