City have opened their campaign with victories against Newcastle United and Hull City, either side of a 3-2 defeat to Cardiff City as they seek to reclaim the title after being runners-up to United last season.
New manager Manuel Pellegrini has been busy in the summer transfer market, capturing the services of Fernandinho, Jesus Navas, Stevan Jovetic, Alvaro Negredo and Martin Demichelis, which Aguero believes puts them in prime position.
"I am convinced we are stronger than last season," he told Gazzetta Dello Sport.
"It will be a really competitive Premier League but we have a good squad to win and I would say we are a little better than United and Chelsea.
"United will be our biggest rivals, even if they have changed coach, and then Chelsea with the return of Jose Mourinho. Tottenham have built a great squad and there is always Liverpool.
"City have invested a lot for some years and is growing a lot and quickly. We know that we have to win and the new arrivals know that City wants to become one of the big teams."
The 25-year-old - who scored his only goal of the season so far against Newcastle - revealed a change of leadership has opened doors for him to move forward.
"With new wide players like Navas and with David Silva, who plays on the left, Pellegrini has asked me to move further forward, almost up with the centre forward, and he asks me to move more in the area and link with Yaya Toure, Navas and Silva," he added.