Best:
Anime: Episodes 139-140, there is just much win in those two eps, Grim vs Ichy, Shinji vs Grim, Uli & Ori, Luppi vs all, and Urahara! Oh and Wonderwice trying to play grabass with Urahara's hat was funny.
Worst:
Anime: Prolly the arc with Matsumoto, such a shame.
edit: So so very very sorry about the spoilers, just completely missed it when i typed it. sorry.