Buffy is the closest thing I have to a religion, having watched every episode probably two dozen times at this point. I think season seven is vastly underrated. It has three of the best Buffy Speeches of the entire show, and the mechanics of The First meant that every interaction turned into a deep character study of the victim in that scene. It also really went deep on the whole allegory of slayer-potential-as-female-empowerment that subtexted the entire show (but was mostly only flirted with until then).
That said, season 5’s season finale still brings a tear every single time. The emotional high point of the series, for me.