"What's your favorite season?"

Translation: 你最喜欢什么季节？

[ashaman5]

a bit strange - i'd say or hear "shi shen me" more commonly. my 2c

[Patrick_Dark]

I think "您最喜歡哪個季節？" ("Which season do you like the most?") is pretty much equivalent and should be accepted.

[DaveLommen]

I think your answer is equivalent to the suggested solution and indeed means: "Which season do you like the most?" I do not think they literally mean: "What is your favourite season?"