I might as well rate it as well.
1. Season 4 - I just love this season. Loved the concept of the initiative, enjoyed the Buffy x Riley relationship more than the Buffy x Spike relationship (but I prefer Spike as a character), loved Spike becoming their prisoner and it had some of the best episodes (Hush, Something Blue, A New Man, Fear Itself, Primeval). And I actually quite like Adam unlike seemingly most other fans.
2. Season 2 - It started of a bit slow, but the Angelus storyline is the best storyline of the entire series in my opinion. The only reason this is not my nr. 1 pick is because season 4 as a whole is better than season 2.
3. Season 3 - Gotta love Faith. I always wanted to see an evil slayer, and Faith certainly didn't disappoint. Also, the Mayor is one of my favourite villains.
4. Season 6 - Probably one of the funniest seasons, solely because of the trio. Also loved Dark Willow and watching Buffy slowly grow up and become more responsible and adult (or at least try). And Once More With Feeling is quite possibly the finest moment of Buffy The Vampire Slayer (besides Hush).
5. Season 8 - I love where this season is going! Twilight seems like an awesome character and I can't wait to see more of Dracula (I'm only up to #12, so I don't know how much of a role he's going to play yet). It's really great to see how much the Buffyverse has evolved when you compare this to season 1.
6. Season 5 - I'm not a big fan of Glory. The season started off great, but eventually it just kind of lost me unfortunately. There were some standout episodes though (The Body, The Gift, Fool for Love, Buffy vs Dracula - if it weren't for the actor who played Dracula).
7. Season 7 - I'm really not sure about this season. I think Spike became a bit too tame in this season and I prefer his character in all the previous seasons, as well as Angel Season 5 (the same goes for Faith actually). It had some great episodes and I loved the season finale, but most of the seasons just couldn't hold up to the previous seasons as far as I'm concerned.
8. Seaosn 1 - It was a great start for a brilliant series, but I rated it this low partially because of the fact that it's only half a regular season. But I did like the Master and the introduction of all the characters.