"¿Cuál es tu deporte preferido?"
Translation:What is your favorite sport?
And that would be a better translation.
In general, the cognate is the best translation.
Would it? I don't really see it. Preferido in Spanish is often used with the same meaning as favorito, like in this sentence.
I understand that what you say is true about Spanish.
Nevertheless, "preferred" has a somewhat different meaning in English from "favorite."
(As this next sentence should illustrate):
Sometimes the "preferable" word doesn't have the same precise meaning (that is, connotations) as the commonly used favorite word.
See my comment below on the distinction between the two.
What is your favorite sport? ¿Cuál es tu deporte favorito? What is your preferred sport? ¿Cuál es tu deporte preferido? Are they equivalent? Your favorite depends on your preference.
I agree the sentiment of your sentence is the same, but it is not a translation of the given sentence in my opinion. Your sentence would be "¿Qué deporte es tu (su) preferido?" o "¿Qué deporte es tu (su) favorito?"
I entered "What sport do you prefer?" and was marked wrong on 8/30/2018. (sigh)
The translation for your sentence would be "¿qué (cuál) deporte prefieres?" or "¿qué (cuál) deporte prefiere usted?". qué deporte = what sport, cuál deporte = which sport (usually comes with options). Cuál es tu = what is your.
You should be able to, although you're missing the accent on the e -> qué. Perhaps you had a different error?
It took me a while to understand the differences. But here is what I have learned:
After "ser", the word "Qué" is asking for a definition. It is for open-ended questions.
"Cuál" is asking for a choice from a limited number of options (it is not open-ended).
To ask for a choice within a group (such as a group of sports), "qué" must be followed by a noun. ("Qué deporte prefieres"? Which sport do you prefer?)
Which is your favorite sport? "¿Cuál es tu deporte favorito?"
See these references: