From Laura K. Lawless,
Your Guide to French Language.

Learn some different ways to say "good" in French

If you want to make your French sound more, well, French, one place to start is with your vocabulary. In French classes, you tend to learn the most common, basic terms. Bon is one example of a very common word that has numerous synonyms to choose between, in both normal and informal registers. Take a look at this lesson to learn some different ways to say "good." Click on each word to hear it pronounced.

Agréable
nice, pleasant, pleasing

Il est toujours agréable de vous voir
It's always nice to see you

C'était une conversation agréable
It was a pleasant conversation

Bien
good, moral, right, healthy

Ça serait bien !
That would be good!

Ce sont des gens bien
They are good (moral) people

Bien is invariable and can be used as an adjective only with copular verbs, like être

Bien is more commonly used as an adverb that means "well."

Bon
good

Bonne idée !
Good idea!

C'est un bon étudiant
He's a good student

Lesson on bon vs bien

Excellent
excellent

Il a répondu en excellent français
He responded in excellent/flawless French

C'est excellent !
That's excellent/wonderful!

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Exceptionnel
exceptional

Il a un talent exceptionnel
He has exceptional talent / He is exceptionally talented

C'est une occasion exceptionnelle
It's an exceptional opportunity

Note that exceptionnel is a semi-false cognate, as it can also describe something as an exception to the norm:
un numéro exceptionnel - special issue

Extraordinaire
extraordinary

C'est un livre extraordinaire
It's an extraordinary book

Elle a connu un succès extraordinaire
She has had extraordinary / immense success

As in English, extraordinaire can mean "out of the ordinary" without necessarily meaning really good:
Il a eu un accident extraordinaire - He had an extraordinary/unusual accident

Merveilleux
wonderful, marvelous

C'était un spectacle merveilleux
It was a wonderful performance/show

Le vin est merveilleux cette année
The wine is excellent this year

Remarquable
remarkable

Il est remarquable qu'elle ne soit pas au courant
It's remarkable that she doesn't know what's going on

C'est un homme remarquable
He's a remarkable man