At last, I've finally got the chance to read this thread and comment!
I watched every episode of Buffy when it was first broadcast on terrestrial TV (BBC2?) and was hooked from the very first episode by the tremendously witty writing. I remember watching the episode where Buffy has to kill Angel in floods of tears. It took me days to get over that! It was such a treat to buy the complete boxset and watch all the episodes through in order. I might even do it again!
Anyway, random thoughts...
I can't choose a favourite season, they were all great (even series 4, which no-one seems to like). Plus another reason I can't pick a fave is because my memory is shocking and I can't remember which episodes belong in which series. There aren't many episodes I don't like, but the one that always sticks in my mind is "Go Fish". God, I really hate that one. It was a stinker. It didn't improve on the second watching either.
The characters... I used to fancy Angel, but to be honest Spike is hotter. Angel's "tortured soul" thing gets a bit wearing and monotonous after a while. I much prefer Spike's honesty - he's evil and he admits he is. Also, Spike gets all the best one liners!
I find it quite interesting that a lot of people don't really like Buffy, seeing her as a whiner, and I used to feel the same. But after my marathon re-watch of all the episodes, I saw Buffy in a new light. I don't think she does complain much, considering what the poor girl goes through! How hard is her life? Sure, she has cool super-powers, but at what cost? She has to juggle being the slayer with school, work, family commitments... A lot of people struggle with those by themselves, without the added pressure of fighting evil! Because she has such a strong sense of duty, she can never just walk away or treat it as fun, like Faith did. Plus, she is incredibly brave: she sacrifices herself (literally) to save others. I think she does a damn good job. And anyway, anyone who has Dawn for a "sister" is entitled to whinge.
So, my favourite characters are Spike and Buffy herself. I couldn't stand Oz, and disliked Dawn, who seemed to spend her time trying to get herself and/or Buffy killed. I liked Willow until she got "above herself" as a powerful witch. I always liked Xander, Giles, Faith, Anya (hilarious) but found Joyce, Drusilla and Tara pretty annoying. And I didn't like the three "uber nerds" and the fact that they were the "big bad" for most of the season.
I'm glad someone else has mentioned the whole "Terra" thing, it drove me nuts.
I think Spike's character was developed the most. When you consider what he was like when he arrived - a pretty conventional bad guy - the way he changed was very interesting. I suppose he changed for selfish reasons, ie he loved Buffy so wanted to do good things to please her, but by the end I think he truly had changed and wanted to do the right thing to make up for his past. And
Well, that's a pretty long post, so I'll stop now. I wonder where Roxi's up to now in her Buffy marathon?