Terrorism
The main issue I’ve got with some of the big bads is that almost all of them weren’t a actual threat.
Ethan Rayne was a pantomime villain, Maggie Walsh and Adam were both a waste of time, the Mayor was extremely weak, The Master was okay but dull, and Glory was a drama queen.
The only big bad that I truly liked was Angelus, but because Buffy wasn’t on HBO, we weren’t able to see him commit any truly disgusting acts.
I really wish that Buffy would’ve tackle the subject of Terrorism, and have a big bad who’s a true anarchist.
Why not have a half-demon who’s also a terrorist? His name would be Dennis Vaughan, and my idea would be that he’s a old rival of Angel’s, and he’s desperate to take control of the Hellmouth.
Have Dennis set off a number of bombs in Sunnydale, and follow it up with him committing random anarchistic crimes. Angel tries to stop him, but Dennis outsmarts him at every turn, which drives Angel to the point of insanity.
As Dennis’s reign of terror grows worse, the National Guard is brought in to protect residents from the Hellmouth, but a unfazed Dennis doesn’t give a damn, and in response blows up a power plant to make a point.
Eventually, Dennis and Angel have a final showdown, and with the help of Buffy and the Scoobies, Angel achieves ultimate redemption by killing Dennis.
I haven’t figured out the whole story yet, but this would’ve been my idea for a big bad.