Vampires would make more sense. Short-term, they're worse. I don't care for our chances against even the weakest if they have that stone. But at least they're likely in it for themselves.

[ He stares through the mirror. Nobody about by day. Could mean vampires or hunters or thieves just as likely as each other. ]

If humans have it- at best, they're hunters. I can talk to them. Most likely, they're some local shithead who wants power and want to be turned, which is- not materially different from them being vampires in the first place. The stone will overcome the initial weakness from the turning process. They'll be a danger within hours, rather than months.

And at worst, that rock still contains the Vampire Lord of the Forest of Eternal Night. And I'm sure that some idiots out there think it'd be a good plan to get him out of it.