We had 3 Wyandottes, we called them the Evils. I finally got rid of two and wished I done it years ago. The whole flock was far more relaxed without the risk of the Evils mobbing. The remiaing Wy is still a bully and is making life hard on my new pullets, but she's a good layer and I'm short on them right now so she'll stay until the pullets start laying. If she's still bullying them when they're grown I will probably send her to the crock pot.
I would say it depends on where they come from. Mine originated with breeder stock and they are nice calm birds....not the least bit nasty or mean. I do hear people complaining about hatchery stock tho and how they aren't the nicest birds.