30 Days of Buffy: Day 20 - Best Spike-centric Episode

Eurgh! This might be a cheat but I'm going to pick Spike's first appearance in School Hard because...

It has a genuinely evil Spike

It has a healthy dose of Drusilla

And it has Joyce with an axe...

... which ripens into a nice gag in Becoming II

So best Spike-centric episode is definitely School Hard!