At any gegeben moment, i would have to say vampires. They're CONSTANTLY a danger, in the sense that they are always thirsty. If they're trying to resist, they can snap at any strong temptation (Taking note of the Jasper incident). You're in constant danger, even if the vampire isn't trying to hurt you.
When it comes to werewolves, I'd say they are only dangerous while phasing. They have complete control over their actions while in human form and wolf form. They're not really dangerous unless they intend to hurt you. They are human protectors, after all. The Wölfe only exist to protect the humans from the vampires, not the other way around.
I would have to say vampires. Namely because they can pass themselves off as human and can get close to Du and lure Du into a false sense of security. Werwölfe when they are at their most dangerous, Du can flat out see that they are dangerous and stear clear of them.
Its really opinion driven. Of course, asking this question, Du will get good Antwort for some, good Antwort for others, and bad for some and others, and so on. I personally say vampires, not just the Twilight vampires, but Dracula, Vlad the Impaler, and so on. So many of historic people (such as Vlad the Impaler) were dark and twisted and then there is the werewolf legend for The Beast, the wolf, etc. So whatever Du choose is basically oponionated but I personally say Vamps FTW!! (for the win)
Both can be very dangerous. I don't think that one is Mehr dangerous than the other. But if had to decide, I'd say the Vampire are Mehr dangerous since they have special powers which the Werwölfe don't have.