Originally Posted by bluebaron

You serious? One of my friends had vBulletin, and he was getting massive spam. And bots continued on registering, even though he added mods, now he switched to IPBoard. SMF/phpBB/MyBB are good forum softwares, you can stick with them. My point is, no matter what software you use you will still get spam bots.

Try adding that captcha, where you have to assemble an image(I think it was a watch?), not sure how its called though. And, after adding that you can always make some math questions, like DiDok suggested.