Aguero, who finished with nine goals fewer than Kane in the top flight last season, marked his return to club action with a couple of strikes as the Citizens beat Chelsea 2-0 in Sunday's Community Shield.
The Argentina international's brace took him past the 200 goals mark in a City shirt, leading to high praise from former Manchester United centre-back Ferdinand.
"Getting 200 league goals for Manchester City is a phenomenal amount, and I think he is the best striker in the Premier League," he told BT Sport. "He was the hardest I played against, with fantastic movement, pace and awareness.
"In terms of someone who is hard to play against, he brings so much off both feet, and with his movement and pace he offers all sorts of problems. Kane is a great player, but Aguero just takes it."
Ten of Aguero's 201 goals in all competitions for City have come against Chelsea - only against Newcastle United (14) has he scored more.