Formal:
* Santé! (This is the most common and formal way to say cheers, similar to "To your health!" in English.)
Informal:
* Tchin tchin! (This is a more casual and playful way to say cheers, similar to "clinking glasses".)
* A votre santé! (This is slightly less formal than "Santé!", and also means "to your health!")
* À la tienne! (This is a more familiar and friendly way to say cheers, meaning "to yours!")
* Bonne santé! (This is similar to "A votre santé" and means "good health!")
For a toast:
* Je vous propose un toast! (This means "I propose a toast!")
You can also use these expressions to respond to someone who says "cheers" to you:
* Santé!
* Tchin tchin!
* A votre santé!
* À la tienne!
Ultimately, the best way to say "cheers" in French depends on the situation and your relationship with the person you are toasting.