The Italian compared the Ivorian to his former AC Milan team mate Marco van Basten and said when he is on his game he is impossible to play against.
"There is a word in Italy: 'trascinatore'. It means the player that pulls the group together. Gennaro Gattuso was the trascinatore at Milan, John Terry is a trascinatore at Chelsea, but Drogba, too," Ancelotti told Tuesday's Daily Mail.
"There are leaders that speak a lot, he can do this, but then he leads by example with the way he plays. This happened from the start for me. There was never a chance he would leave. He is far too important for us.
"I know some see him as a prima donna but the difference between a prima donna and a leader is a centimetre. The leader uses his talent for the team, the prima donna for himself, but Drogba has never been a prima donna for me.
"He reminds me of the great players, the way he has been this season. If he is feeling a good sensation about the game, if he is confident, he is impossible to play against.
"I used to play with Marco van Basten. I asked him how we should give the ball to him. He said, 'Just pass it, and then start running to congratulate me'. He always thought he would score, and he was usually right. When he is at his best, Drogba can be like that.
"I have never played with a stronger striker than Didier. Filippo Inzaghi at Milan was a smart guy, Andriy Shevchenko was strong, but not in the air, Hernan Crespo, Alessandro del Piero - Didier is different to them all. I think he is one of the best in the world right now. I would put him alongside Zlatan Ibrahimovic, Fernando Torres and Samuel Eto'o but I would not swap him for any of them.
"Didier has it all. When you find a player who has talent and is unselfish: hai vinto. You've won."
Ancelotti, who took over at the start of the season, said he was frustrated by the language barrier in his early days at the club but is now able to communicate well with Chelsea's multi-national squad.
"When I first came there was too much distance between me and the players," he said. "I like to joke with them, I like to speak with them - to me it is very important and I could not do that. Now we are closer. I think at first they considered me only as a boss and I did not have the language to break through.
"Sometimes you need to get after them with strong words, but it is more important to explain and resolve the problems on the field. So I don't throw tables: I talk.
"Only one time have they upset me and that was in a friendly match against Reading. We were losing 2-0 at halftime and I wanted to be angry but I didn't have the words to convey that emotion. It is hard to be angry in another language."
