The Senegal international moved to Bayern Munich in the summer after six successful years at Anfield which saw him claim Premier League, FA Cup, League Cup and Champions League honours.
Liverpool swiftly replaced the forward by splashing a record breaking £85million on Benfica star Darwin Nunez.
The Uruguay international made a promising start to his career in England after helping the Reds to the Community Shield last weekend.
Despite this, Lescott feels City have the upper hand heading into the new campaign.
He said: "I think the top two teams are going to be City and Liverpool and I think City are the favourites due to them winning last season.
"I think you should be favourites if you are the reigning champions but also I think they've added to the squad with some quality.
"I think it's going to be slightly more difficult for Liverpool. I know they've signed Nunez, but without Mane, they can't be as strong.
"The same could be said about Manchester City losing Raheem [Sterling], but in regards to Liverpool losing Mane I think that's a huge loss."
Sterling moved to Chelsea after seven successful seasons at the Etihad which saw him claim 10 major trophies. Gabriel Jesus and Oleksandr Zinchenko, on the other hand, both made the switch to Arsenal.
Lescott, who works for BT Sport as a pundit, added: "I think they all improve the teams that they are joining because they are world-class players in their respective positions.
"City will miss them as personalities, 100 per cent, but I think if you look back and view Man City the team, the style and how they play, I think Pep has created a system that isn't reliant on any individual.
"So it's probably not as damaging (on the field) as the impact in the dressing room. They'll all be missed for that reason but players move on."