What movies do you like best 这种说法正确!
What movies do you like best =What kind of movies do you like best =What type of movies do you like best
以上三句是一样的意思,"你最喜欢哪种类型的电影?"
What movie do you like best?
"你最喜欢哪部电影?"
What movies do you like best 和What movie do you like best?两个句子有区别.