Good gravy, folks, the show isn't called Buffy for nothing. Faith was gorgeous, Tara had the best voice, Willow was the cutest, Dawn went from whiney kid to serous jailbait ("Him," season 8 as I recall).
And I concede that SMG went a littlle anorexic in the last two seasons. She was cuter plumper.
But, that said, Buffy/SMG had the sexiest MIND. Her body was okay (and she was a competitive figure skater before she became an actor full time; likewise she studied Tae Kwan Do for a year or so. But it was her personality radiating through her physicality that knocked everyone else into the weeds.
Consider these Hotness of Buffy moments:
1. S2Ep13 Surprise--when she seduces (okay, that wasn't too hard) Angel. Melting.
2. S2Ep16 Bewitched, Bothered & Bewildered, when Zander becomes irresistable to all females and Buffy throws herself at him wearing only a coat and a pair of high heel shoes. Lord have mercy.
3. S4Ep14 No I in Team I believe--scene that intercuts between Buffy & Riley killing demons & making love.
4. S5Ep1 Buffy vs. Dracula --when she sucks his blood. Yee-haw. That was before the thrall was gone.
5. S6Ep9 Smashed --when her lovemaking with Spike literally brings the house down. Even Faith couldn't match Buffy for sheer feral intensity when Buffy put her mind to it.
6. S6Ep10 Wrecked --SMG hated doing this episode, but the scene with her and Spike in the Bronze is seriously out there.
7. S6Ep11 Gone --the sexiest scene I've ever seen in which one of the parties (Buffy) was completely invisible.
and of course
8.Angel S1Ep8 I Will Remember You when Angel becomes mortal for a day. True love is the hottest hotness of all, when all is said and done.
In other words, hotness isn't just sexiness, and Buffy's got that extra something, even when she isn't trying to be sexy. Remember when Cordy wished Buffy'd never come to Sunnydale and she shows up at the end, a grim, scarred veteran? Be still my heart!