KeyCaptcha in my opinion the best plug-in. I use it on my three sites. I've used another Captcha before, but it did not give me a 100% guarantee, and sometimes it was hard to recognize the text even to me. KeyCaptcha unlike other plug-ins built on the principle assemble a picture from the pieces. It's easy. Even a child will not have difficulties to pass such a test. It's easy to install, easy to use. I want to thank the technical support for their efficiency in solving of my non-standard problem.
Thank you for your review