You need ALL the tools - the reg form timer, connection to the forum spam stopping services and a good QA or captcha. You can also decide to not let certain countries in..which I think is good unless your forum really has folks from those countries!
After all of that, looking at the first post (moderate) can catch any who get through.
It is a service which utilises the Stop Forum Spam, and their own database to basically kill registrations before they even happen, since installing it a few days ago I have had no registrations from bots, after being literally bombarded previously.
Dan Cryer is the author, I have known him for years and years from our Invision days, he worked for IPS for a while too.
Also my suggestion is to use incapsula. It is like cloudflare but much better because you can configure to not show annoying captchas and pages when visitors have some issues with your forum. Also incapsula have list of bad bots that and will block spammers.
Also you need only to change dns to your cpanel to use incapsula + there are some features that will slightly increase forum speed by caching (CDN). Configuration is super easy! IMPORTANT!Incapsula free package offer 50gb monthly bandwith! check packages here: http://www.incapsula.com/pricing-and-plans/compare-all-plans
Below is screenshot of my incapsula blocked bots log.