Ardiles told the Daily Star Sunday: "Of course, it's a huge amount to spend on a player but looking at today's transfer market and the prices being paid, £25m for Carlos definitely isn't too bad.
"Tevez is a wonderful player. He was a big hero at West Ham and a big hero at United. The English fans love his never-say-die attitude. He is a fantastic acquisition for City and I think it is definitely United's loss - like the majority of people in Manchester do.
"His qualities go beyond just what he does as a player. He's a huge influence on his team-mates too. That's why he's a regular in the Argentina side - both under the previous coach and now with Diego Maradona. He is hugely respected at home. And he's so much more than just a striker. He can play anywhere, right up front or behind the strikers being creative - which is where I like to see him best.
"His workrate is incredible, second to none. That's why, out of all City's major signings, he will be the first name on Mark Hughes' teamsheet."
Ardiles is baffled by Sir Alex Ferguson's apparent indifference to securing Tevez's signature and disputes the version of events suggesting the player ignored contract talks.
He added: "City was his second choice - he was incredibly happy at United and loved playing for one of the really big clubs.
"I know if United had made him an offer while he was there, Carlos would have signed and stayed."