If it wasn't for the fact that my faucet script isn't using any captcha at all, I'd be using bitcaptcha. Nice captcha once you have it up and running. Somewhat sensitive to popups/-unders but otherwise stable.
I think you'd better choose a security product to protect your site, especially faucet sites.
My faucet script is using a custom security feature that makes captchas largely redundant, but thanks for the concern. I do like bitcaptcha and I would use it again if I did need a captcha.
The one issue I have with the captcha is that popunders mess it up (lots of page reload which is annoying to users), if that particular issue could be solved it would be perfect. Heck, I'd install it again just for the extra ad-revenue, lol.