Sort:  

Total vote count, including weight. It's gonna be pretty hard for the annoying bots to maintain an overall positive karma, especially the really prolific ones. I just hope it can be done in a computationally inexpensive way for nodes (I don't see any reason why it can't, there shouldn't be a need to recount every time).

I can see a way around it. The bot just needs to set it's vote karma to 0 and have other bots upvote it so it can vote.