I use Avast Free, but as Skuzzy said, there's really no free I could recommend.
Truth to be said, having seen almost every Anti-Virus program within my clientele, each one of them has flaws every now and then. One trick is to put AH on every exception list you can find in whichever program you're using. That might, just might help a little bit.
As for the title, there's many other things you can do for safer browsing than just having an AV running in the background. Choosing a non-spying browser and search engine is a good start. Modifying your browser settings to at least clear the history automatically at each shutdown is another easy-to-do trick. Adblock and Disconnect don't really hinder anything essential, instead they block many misleading ads. An even safer approach would be to set everything from "allow" to "ask each time" and then slowly creating a whitelist by permanently allowing selected functions for certain trusted sites.