Can I not vote yet, or at all? I can explain why!
For years I've tried to decide which season is my favorite. Every once in a while I changed my mind. I thought it was season 6. But I've decided that it's not very fun. So much Spuffy just isn't enough for me to make the season enjoyable. It's too dark. And I don't just mean the atmosphere, but also the way it was shot. If seemed darker.
Season 3 is a little bleh to me. Not because it's not good. But I have a few problems with it I guess. For one, Faith annoys me. Secondly, Buffy and Angel annoy me, they ruined the season, they kept breaking up and getting back together every other episode. Third, no enough Spike. Those are just my guess as to why I don't really like this season.
Season 4 is so fun and I enjoy it a lot. But it has too many problems. That doesn't stop me from liking it very much. But I'm not sure if it's my favorite. Sometimes I think it is. I think it's the one I enjoy the most, it's my most watchable one.
Season 2 is classic, and I have a weakness for it because of it. It was pretty much perfect. Pretty much. So it might be my favorite.
On the other hand, there's season 5. Which is as good as season 2, IMO. Very intense. But a little depressing in the ending. Not because of Buffy's death, but because Dawn doesn't die.
Seasons 1 and 7 I don't really put on the list of my potential fave, because they're last on my list. And this is your favorite season, so why keep talking about them?
Conclusion: I'm not voting.