Surprised that S6 was higher than S1 but there are quite a few gems to be had waiting for you in S6 too - 3 of my top 6 episodes are in Season six. But as far as I rank, its never as consistently good as in season 4.
My favorite episode of the series is in Season 6 also, but it's not really a fan favorite around here and I suspect Screed
will similarly vote it down as such. I'll keep the suspense until we get to the episode so as not to give away my secrets.