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.
I liked some of the poems, but not all of them. I did not understand all of the poems. How did pirates end up in a Christmas poem? My favorites were the first, the one by Rudyard Kipling, and, surprisingly, Edgar Allen Poe. There were one or two others I really liked, and some that were nice. It was a nice Christmas treat.
This is a collection of clumsy, odd and awkward poems, often by famous authors. I'm not impressed. I bought this, hoping it would be an annual read. It won't.