I've been thinking about this question, and while I'm not a fan of Dollhouse I'm not sure I want Buffy back for a few reasons.
1. It's been like five years. The actors have all moved on to other stuff. Aly is on HIMYM, Amber has her books etc. Now some of them like Nick and Emma haven't done much since it ended... They have all aged though, they would need to do a time skip plot or something.
2. While Season 7 wasn't my favourite and the final episode was really sad because we lost someone amazing, I think it ended on a really powerful note.
3. While I haven't read the comic yet, I can only assume that it can take the series in directions that the show couldn't reasonably do.
Now, an animated Buffy series! I would trade Dollhouse for that in an instant. Either the highschool years deal, or an animated Season 8 with the cast back doing the voices. I'd be totally down for that.
Sorry if this was too long and not worth reading...