Verratti has developed into a key figure at PSG since joining the club from Pescara in 2012, establishing himself as a first-team regular under Laurent Blanc.
The 23-year-old's form has seen him linked with Real Madrid and Barcelona in recent months, with Cavani confident his colleague would flourish at either Spanish giant.
"Verratti is a phenomenon who could play for any big team in Europe," Cavani told Marca.
"He is the best player I have ever played with, both for the way he plays on the pitch and for his behaviour off the pitch. He is a great guy, always positive and very nice. He has class and elegance. He sometimes looks like a veteran already.
"If he continues to work like this, he will continue to be one of the best there is. It's a joy to be playing with him."
Like Verratti, Cavani has been heavily linked with a move away from PSG, with Juventus believed to be keen to lure him back to Serie A.
He recently admitted that he feels flattered the Turin side are keeping an eye on his situation, but no decision has been taken on his future.
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Cavani added: "There is always a lot of talk about my future. On the one hand it is a good thing because it shows clubs are keeping tabs on me. But on the other hand it is a bad thing because it suggests I am not happy at any club, which is simply not true.
"Have I received any offers? I can only say that I have a contract for two more years and I will respect it. But then again, you never know what happens in football. There are a lot of things that are out of my hands.
"Something could happen, but it all depends on how the season ends and on what the club want. It depends on those things whether I will move on or stay put. There are a lot of factors that need to be taken into account."