1. What kind of movies do you like?

2. I like comedy.
3. I like comedies.
4. I like comedy movies.

(Which answer is right? Are all OK?)

5. What kind of books do you like?
6. I like fantasy.
7. I like fantasies.
8. I like fantasy books.

(Which answers are right? Are all OK? Which answer is commonly used? Thank You.)

1, 2, and 3 are fine. 4 is not used.

5, 6, , and 8 are used, although 5 and 6 are most common.

All of the answers are correct and convey the same meaning. In both cases, the preference for a specific genre is being expressed. The choice of words depends on individual preference and style. However, it is more common to use the form "I like comedy/comedies/comedy movies" or "I like fantasy/fantasies/fantasy books" without a specific preference for any one form over the others. Ultimately, it is up to personal choice how you want to express your preference for movies or books.