Well, two or three years ago I would say that it could be a UI problem, but now I think that most users are familiar with reCaptcha and similar approaches. You can try activating only Akismet at the beginning and see how it goes.
@onthebeach96 I had the same problem as you with phpBB. I was getting bombed every hour by spam. When I installed BBPress I forgot to activate Akismet, and although spam users where registering they didn’t post anything (maybe because the bots weren’t ‘smart’ enough to think that the password was emailed at them). By activating Akismet and reCaptcha plugin no spam users have appeared.
