He's a great CB but I honestly don't get the hype around him being called the best in the world. He was obviously going to win titles with PSG given their strength, but other than this season never accomplished much outside of French/Italian competitions, either with AC Milan or PSG.
I wouldn't really say any CB is by far the greatest of this generation. Each has their strengths and weaknesses. Ramos, Boateng, Pique, Silva, Bonnuci, Godin, VvD, Varane, Chiellini, Hummels all are top class defenders during this last decade (pretty sure I'm missing a few others).
My top 3 for would be Ramos, Boateng and Bonnuci.