If you are willing to go paid, OpenDNS offers secure DNS with parental controls – that can also be used at businesses to restrict certain types of sites. The free version too has parental controls but I doubt it offers secure servers.

Among the free without parental controls but good security are the Google servers followed by Comodo servers. None of these two are fast or offer filtering based on content. But they do filter off malware affected sites.

The above is my observation. I do not know the scope of any DNS service to be able to offer protection against all types of malware… esp CryptoLocker.

But thank you for the question. This triggers an idea to get a list of freely available DNS using NameBench software. Then I can check out the top ten free DNS services for what all they offer. I cannot post it however, as the results will vary from place to place.