Formal:
* Il est incroyable. (He is incredible.)
* Il est formidable. (He is formidable.)
* Il est extraordinaire. (He is extraordinary.)
Informal:
* Il est génial. (He is awesome/great.)
* Il est super. (He is super/great.)
* Il est top. (He is top/awesome.)
* Il est incroyablement bien. (He is incredibly good.)
More specific:
* Il est un homme extraordinaire. (He is an extraordinary man.)
* C'est un mec génial. (He's a great guy.)
The best way to choose the right phrase depends on the context and your relationship with the person you're talking to.