Best captcha?

[NeoCHI]

I know this has probably been asked a billion times but most of them are kind of old and this kind of stuff changes all the time so I was wondering which captcha works the best currently?

I've been using the KeyCaptcha for all my forums but it doesn't seem to do a great job cause there's still plenty of automated spammers getting through everyday...

 

[Chris D]

We use reCAPTCHA (No CAPTCHA) here.

We still get a fair few spammers through but they will generally be human spammers.

 

[Robru]

I use Slider Captcha and never bothered by spam

 

[whynot]

so I was wondering which captcha works the best currently?

Question and answer, provided you are updating them regularly.
The timer helps a lot.