Formal:
* Fascinant: This is the most direct translation and is suitable for most situations.
* Captivant: This translates to "captivating" and implies a strong hold on your attention.
Informal:
* Passionnant: This means "passionate" and suggests a strong interest in something.
* Intéressant: This means "interesting" and is a more general way to express that you find something appealing.
Other options:
* Époustouflant: This translates to "breathtaking" and suggests something that is truly awe-inspiring.
* Extraordinaire: This means "extraordinary" and implies something that is remarkable or exceptional.
The best choice will depend on the specific situation and the level of formality you desire.