The Holland defender left Bournemouth for City after the Cherries' relegation.
Ake told the Manchester Evening News: "There was interest from others but I'd rather not say which clubs. I made the decision to come here, I spoke with the manager, had a good conversation with him and when a club like City comes in for you, just knowing you're going to learn so much and being able to play with players like this and train under a manager like this, I just knew I could develop myself even more.
"I think I'm at the perfect age now where I can learn and develop and I thought it was the right place to do it.
"The manager has improved so many players over the years and that's what I'm looking to do as well to come here at the beginning of the week and work with him to try and see where I can improve tactically, what he expects of me. I'm just looking forward to hopefully taking my game to the next level.
"This is where you want to be ultimately. There's not many higher clubs you can go to. I'm so happy at the moment and am looking forward to learning from one of the best managers in the world and the best players in the world. I'm excited to see what is going to happen in the next 12 months or so."