I just have to say that I loved the depth of emotions that Ergo explores: Love, Hatred, Duty, Loneliness, Friendship, Sadness, Joy... It's a truly expressive series, in my opinion, and it offers an interesting look at things such as religion and the complexities of non-human relationships. I also thoroughly enjoyed the opening and closing segments, and I thought that they captured the mysterious, ethereal, religious feel of the series quite well. I'd have to say it's between this, R.O.D. the TV, and Planetes for my favorite series.