The Ivory Coast international centre-back was released by City in May at the end of his four-year contract.
Toure only made 10 Premier League starts and five substitute appearances in his final season under Roberto Mancini, with Matija Nastasic and Joleon Lescott both ahead of him in the pecking order.
The 32-year-old feels he should have been retained at City but that their loss is Liverpool's gain.
"I was better than certain players at Manchester City but I was left on the bench," Toure told The Sun.
"Before I left the club, I told the people in charge that they would regret letting me go. People said I was finished and that I could never get back to my former level.
"But now I am at Liverpool - and I am sure that City must be kicking themselves when they see how I am performing."
Toure likens his own situation to that of brother Yaya, who was sold by Barcelona to City in summer 2010.
"I have had a similar experience to Yaya," he added. "Managers come to clubs bringing players with them and they want to pick them at all costs - whether they are any good or not.
"Yaya was much better than Sergio Busquets at Barcelona. But he was behind him in the pecking order and he found that hard to accept.
"I advised him to come to Manchester City while I was still there.
"He listened to his big brother's advice - and now he is the big boss on the field for them."
City play host to Liverpool in the league on Boxing Day in what is likely to be a crucial top-of-the-table encounter.