Half Blood Prince!
and then Deathly hallows...

1.HBP
2.OOTP
3.DH

1. PPA
2. OOTP
3. GOF
4. HBP
5. SS
6. DH
7. COS

1) Goblet of Fire
2) Deathly Hallows
3) Order of the Phionex
4) Prisoner of Askaban
5) Half Blood Prince
6) Chamber of Secrets
7) Sorcerer Stones

BY far my fave one<3

all are amazing, but Deathly Hallows so far!!!!!
I) Deathly Hallows <3
II) Goblet Of Fire
III) Half Blood Prince
IV) Prisoner Of Azkaban
V) Chamber Of Secrets
VI) Philosopher's Stone
VII) Order Of The Phoenix

Deathly Hallows and Order of the Phoenix. I think my least favourite is the Chamber of Secrets.

I say my favourites are in this order :)
1. Deathly Hallows
2. Prisoner of Azkaban
3. Goblet of Fire
5. Half Blood Prince
6. Order of Phoenix
7. Chamber of Secrets
8. Philosopher's Stone

My favourite scene in any book is in here. The mirror of Erised chapter is the most emotionally charged, in my opinion, scene in any of the books.

and DH.