Moving to XenForo 1.2, I enabled all the DNS block lists (Stop Forum Spam, Project Honey Pot, etcetera), and nothing else - not even e-mail verification or CAPTCHA. We've had maybe four or five spammers get through the filters since September - not for lack of trying, mind you, many get caught in the moderation queue or just killed silently. But we've also had virtually no false positives, and the user experience is far more appealing to our user base, who tend to have... very short attention spans. The only minor drawback (if you can even call it one) is that some members can get caught in the moderation queue, so we just keep an eye on it and approve the real members as we see them.
This particular strategy probably won't work for larger boards than us (175,000 posts, 50,000 members) - and perhaps it won't work if we grow enough to attract the proper spammers, rather than the drive by XRumer skiddies. But it is a testament to the power and versatility of XenForo's built-in anti-spam features, and I have a paid copy of @tenants' anti-spam bundle if it ever comes to that. But the thing is, I have plenty of excellent options to choose from to murder spambots, and right now? I've got a solution that the vast majority of our users will never notice, but stops roaming spambots.
That's pretty much the best possible scenario.