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.
OK, so...MUCH better stories and art than in Volume One, so that's a great thing. The creators involved in this collection are a Who's Who of Bronze Age talent: Archie Goodwin, Esteban Maroto, Jose Gonzalez, Wallace Wood, Doug Moench, Len Wein, Gerry Conway, Mike Ploog, Frank Brunner, Jeff Jones, Frank Frazetta...I could go on and on. Great stuff.
The bad...wow. Dynamite must give zero fucks about quality control. I remember people bitching about problems when these were released in hardcover years and years ago, and they seem to have not made any corrections at all for these paperbacks. There are at least ten missing pages in this collection, maybe more, pages printed out of order...it's just a mess. (Adding insult to injury, the missing pages are replaced here by black pages, so they should have KNOWN pages were missing.)
Unlike most "fans", I will not curse Dynamite and vow to never buy another volume from them. I'm grateful to have what we do. (I'm against piracy, but in a case like this, where I've paid for a flawed collection, I have no issue visiting a pirate site and looking for the missing pages.)
Here's hoping Dynamite steps up the quality control in Volume Three....