Hunter x Hunter is way up there because it was my first anime and I really enjoyed the story, the characters, and when I watched it. I was on vacation and It just makes me so nostalgic when I think about it. Who cares if its fan serviced, I loved every second of the show.
Blue Exorcist was a great one because I was super into the story. Rin was by far a super bad ass and I hated his brother. I liked it because for a bit it was some slice of life which this anime got me into that genre.