Anybody that has been on the web long enough knows that it is crawling with bots and nasty stuff just trying to spam you from all the possible chan...
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I still work with Google because I think it's very simple and it works extremely well. Even though I'm supporting a big company, it's a great opportunity for me. And most important: It doesn't bother the user any more from v3 on! :)
I only use recaptcha, it's the best one out there. I have many sites, so I constantly need to test captcha so that people can pass it. To do this, I use this service rucaptcha.com you probably already heard about it, it is quite famous among site owners.