The 27-year-old Argentina international reached three figures in Tuesday night's 1-1 draw at Newcastle, his 147th league appearance, a feat bettered only by Alan Shearer.
Sterling, who returned from a five-game injury lay-off as a second-half substitute at St James' Park, told CityTV: "He's a great player.
"A player who can always score goals is a massive asset to your team, and he's a player that can score at any moment...in any football match, so it's massive to have a player like that in your team.
"He's definitely up there with the world's best strikers because he is a player who scores goals in big games and who scores decisive goals. That's the sort of player he is."
Aguero's milestone strike should actually have been ruled out with replays showing he was offside when Aleksandar Kolarov picked him out with a driven 15th-minute free-kick, but City failed to make the most of their good fortune on the night.
The lead was cancelled out by a rare strike from emergency full-back Vurnon Anita, his first goal for Newcastle since March 2014, and had keeper Joe Hart not pulled off a point-blank save from Holland international Georginio Wijnaldum in injury time at the end of the game, Rafael Benitez's men might have collected a second successive win.
Third-placed City now sit 12 points adrift of leaders Leicester and seven behind Tottenham and although they are five clear of derby rivals Manchester United in fifth with four games remaining, their hopes of clinching automatic Champions League qualification are receding.
Sterling said: "It's very disappointing, We had the 1-0 advantage and for third place, we have probably got to defend it a little bit better, and that's all of us as a group.
"We know we want an automatic Champions League place next season, that's the target for this football club, and the two points lost here are quite a loss."
Source: PA