Various is the correct author for any book with multiple unknown authors, and is acceptable for books with multiple known authors, especially if not all are known or the list is very long (over 50).
If an editor is known, however, Various is not necessary. List the name of the editor as the primary author (with role "editor"). Contributing authors' names follow it.
Note: WorldCat is an excellent resource for finding author information and contents of anthologies.
This sampler gave much longer extracts than the usual. I found that it gave a real impression of what the stories were actually about and decided that I don't Would really like to try a couple of them especially Smoke the last story in the sampler