If you can watch any episode of an anime, it should qualify as one of the best animes of all time. This is one of those animes. You don't need to watch anything prior to an episode to know what's going on (bar a few of the episodes.) You can just enjoy the humor, music, theme, and little story each episode has on its own. (Unless of course, it's one of those 'neccessary episodes'. You know what I mean. Well, I can't really explain it all that well. )

Like..

(SPOILER)The last episodes, and the episode with Ballad of Fallen Angels are all I can think of now.