As a writer, unless there was a really obvious masthead, I always do a "Dear Editors". As an editor, while I do appreciate seeing that people looked at our masthead and address us by name, I definitely don't expect it and am totally fine with generic. However, we (a team of three women with a pretty clear masthead) occasionally get emails addressed to "Dear Sirs" and I can tell you that's a quick way to get an instant rejection. 😅