I used to be a huge fan of Bleach, watching nearly all of the arcs, up until the end of the Aizen arc, the arcs after that didn't interest me as much.
The Soul Society arc is epic and is probably the most memorable anime series I've ever watched.
The Arrancar arc with Hueco Mundo is also a contender, it's such a great series and full of evolution and action.
Another anime I used to watch is Inazuma Eleven, I've again watched all the main arcs up until everybody is past their prime. What drew me into Inazuma Eleven is the football as a concept but with supernatural abilities thrown in there to give a twist to the game. It's a great anime for football lovers.