The former England international believes that the Tottenham defender would walk into the City team and would make Liverpool Premier League title contenders.
Merson has also claimed that the 29-year-old former Atletico Madrid defender is worth £40 million at least, and has urged Spurs to retain his services beyond this summer.
“Tottenham need to throw money at Toby Alderweireld if their team is to stick together,” Merson wrote in The Daily Star.
“He is the best centre-half in the world and Spurs just cannot afford to let him go if they want to remain contenders.
“I’m sure if he had been playing, Spurs wouldn’t have caved in to Juventus. Alderweireld would walk into the Manchester City team he’s that good.
“Imagine him at Liverpool – he and Virgil van Dijk would make them major players in the title race again.”
Merson added: “He is worth £40m at least and it would cost Spurs £35m to replace him with someone half as good.”
Alderweireld is one of the best defenders in the world and is a key figure in the current Tottenham team.
According to The Daily Mail, the former Ajax star earns £50,000 per week as salary at Spurs at the moment.
The Sun has claimed that Manchester United are interested in signing the Belgian centre-back in the summer of 2018.
Although Spurs have done quite well despite missing Alderweireld due to injury for a chunk of the season, it is important that Tottenham do not sell him in the summer 2018.