One piece. 900+ episodes with the recent arc having top notch animation. I love that it takes everything from the manga and doesn't skip details. The animation gives a lot of scenes a much more powerful effect (Like luffy confronting the 3 admirals or when Garp visits Dadan after the war)
Brotherhood is definitely one of the best anime I've watched, and also love Death Note. Going to go on another anime binge soon and thinking about rewatching Shippuden again
Definitely "Samurai Champloo", a very good adult story, which mixes samurai with a hip hop sound in some moments, although it has a "not 100% good" ending is still an excellent anime.
It is worth checking out "Basilisk Kouga Ninpouchou" too!