Top 5 with honorable mentions:
5. Fullmetal Alchemist Brotherhood
4. (very conflicted about this slot, but at the moment, it's...) Kyoukai no Kanata
3. Death Note
2. Eden of the East
1. Attack on Titan
Honorable mentions:
- Tokyo Ghoul (previous #4 before I rewatched Kyoukai; animation ruined it for me.)
- Blue Exorcist
- Toradora
- Free (not Eternal Summer.)
- Angel Beats (loved it to death, but I couldn't put it in Top 5. Definitely #6.)
- Clannad (I guess.)
- K-on! (because guitars and stuff.)
- Parasyte (oh, how I wish it didn't do what it did. Dropped after episode 16.)
I'm sure there's more, and I'm sure I'll update this in, like, a month.