I Love The Deathly Hallows! It's definitely my favorite book.

But I also like the Prisoner of Azkaban because its the only one where Harry isn't in mortal danger and it ends happy :)

Dealthy Hallows!!

Prisoner of Azkaban

Definitely my favorite, although I loved all of them. 

I am done with 1 and 2 and i am half way done on 3 and i have 4,5,6,7 to read but i have seen all the movies and loved them