How do you ask what color prefer in French?

There are a couple of ways to ask what color someone prefers in French, depending on the context:

Formal:

* Quelle est votre couleur préférée? (What is your favorite color?) This is the most straightforward and polite way to ask.

Informal:

* Quelle couleur tu préfères? (What color do you prefer?) This is a more casual way to ask.

To be even more casual:

* Tu préfères quelle couleur? (Which color do you prefer?) This is the most informal way to ask.

You can also use "de quelle couleur" (of what color) in a sentence:

* De quelle couleur tu aimerais ton nouveau vélo? (What color would you like your new bike?)

Remember to conjugate the verb "préférer" (to prefer) according to the subject:

* Je préfère le rouge. (I prefer red.)

* Tu préfères le bleu. (You prefer blue.)

* Il/Elle préfère le vert. (He/She prefers green.)

* Nous préférons le jaune. (We prefer yellow.)

* Vous préférez le orange. (You prefer orange.)

* Ils/Elles préfèrent le violet. (They prefer purple.)