I've stayed in 5020 and 5520 on the Wonder (same secret porthole as on the Magic). I've not stayed on the deck 2 porthole rooms, but have heard great reviews of them. It's a toss-up. If you have kids, the clubs are on the same deck as 5, so very easy to get to. The deck 2 rooms are only one deck up when you get off the ship, so super easy. They're also one the same deck or one deck from the dining rooms.
We had a bad experience in our last secret porthole (they were doing maintenance work in the theater just below our room at all hours of the night and kept us awake), that pretty much turned me off of booking another secret porthole again, but that was just that time. It wasn't constant and I think it was isolated incident. However, I'm stubborn and I'd probably not book one again. Those who have stayed on deck 2 have had rave reviews!