1. Sorcerers Stone--Thing
2. Chamber of Secrets--Place
3. Prisoner of Azkaban--Person
4. Goblet of Fire--Thing
5. Order of the Phoenix--Place
6. Half Blood Prince--Person

I don't know who HBP will be. Nobody does. What I think is more interesting is what the HBP will mean to Harry? Remember that in Book 3, Harry thought the POA was an enemy but then discovered Sirius Black was actually his friend. Do you think that Harry will find that the HBP helps him in some way? I wonder if he will teach Harry how to use some extra power or some forgotten enchantment.