Formal:
* Bravo! (This is the most common and versatile option.)
* Excellent travail! (This literally means "Excellent work!")
* Bien joué! (This means "Well played!" and is often used in a sports context.)
Informal:
* Super! (This is a very common and casual way to say "Great job!")
* Génial! (This is a more enthusiastic way to say "Great job!")
* Top! (This is a slang term that means "Great job!")
You could also use a more specific phrase depending on the situation, for example:
* C'est magnifique! (This means "It's magnificent!" and could be used for a piece of art or a performance.)
* Tu as fait un super boulot! (This means "You did a great job!" and is a more personal way to say "Great job.")
Ultimately, the best way to say "Great Job" in French is to choose the phrase that feels most natural and appropriate for the situation.