I disagree. People paying attention don't even have to own the PHB at this point to be able to get a ton of knowledge of the game, including how the "non-basic" classes are shaping up. We already know what the key new principles are (such as bounded accuracy, concentration, multi-class mechanics, legendary monsters), and many of us have been playing with the "official" rules for over a month now. We have a bunch of monsters out, between the Starter Set, the PHB, and the HotDQ supplement. At this point, I feel confident that I could go on playing 5e without ever reading the DMG if I wanted to. And I don't see how seeing the rest of the monsters in the MM will affect my opinion.
I have no trouble at all saying this is my favorite edition; and given that "picking favorites" is one of the most personal and subjective processes in existence, I don't really see how you could be surprised that people are picking favorites. If you feel that you can't answer this poll adequately until reading the first three books, that's fine. It's your choice of "favorite".