Blackbeard is the best One Piece villain indeed. He's actually the most faithful pirate the series has:
- Pirates plunder, murder, rape and do all kinds of atrocious things;
- Pirates might ally with the government if it's advantageous for them;
- Pirates usually don't fight their enemies directly (except if they're weaker), but use schemes and dirty tricks to attain their goals;
- Pirates betray each other very often and might also organize a mutiny against their own captain;
- A pirate crew isn't a cohesive group, but a bunch of lowlifes with their own agendas.
Teach and his crew have everything above and more. Ironically, the real-world Blackbeard wasn't as cruel as him, he was actually a gentleman (probably hailing from a noble family) and barely killed anyone, according to most known sources. Maybe One Piece's BB was also based on Henry Every, as he was more ruthless, was considered the "King of the Pirates" in the 17th century and BB was supposed to be named "Everything D. Teach" at first.