Excel Saga is brilliant, but only if you've seen a broad range of anime beforehand. Every episode is a parody of a different genre and tropeset.
Unfortunately, they run out of ideas about 12 episodes in, and the series quickly devolves in quality after that. They then get very meta and the characters become self aware that certain events are happening solely to 'prop' up the series as the creators run out of ideas, which was cute but didn't save it.
That might've been my main reason for not enjoying it as I had a narrow-minded idea of what anime was.