Berserk - Despite a rather meh start, it built up to be incredibly epic dark fantasy.
Naruto - Good shonen that I still like, but just doesn't strike like it used to.
Fullmetal Alchemist - Amazing. Compact, well built, interesting, great cast of characters.
Dragonball - Classic. Loved the earlier arcs, but it just dragged.
Mushishi - My vote. I just love the eerie mysterious athmosphere. The episodic structure works perfectly for this concept. Which makes it enjoyable not only as a whole series, but by chapter-by-chapter basis. I just love how this manga feels.