1). 'Harry potter and the Half- Blood Prince' is definitely my all time favourite. I just adore it. Snape is so great ..
2). The Order of the Phoenix - it has the best film adaptation in my opinion.
3). The Deathly Hallows - now I am reading it in English too.
4). The Goblet of Fire
5). The Prisoner of Azkaban
6). The Chamber of Secrets
7). The Philosopher's Stone
1. Half Blood Prince
2. The Deathly Hallows (these first two are more or less equal)
3. Order of The Phoenix
4. Prisoner of Azkaban
5. Goblet of Fire
6. Philosopher's Stone
7. Chamber of Secrets
Favourite book is Order of the Phoenix though that also is the longest so it took a long time to read but was worth it, but overall all are good reads.