I have Kaspersky on my desktop and Avira on my laptop. I like Avira free, but dont like ads. (for their products only mind you.) Kaspersky Free doesn't do that (yet.) Both stop viruses very very well. Avira's scanner is slower. I'd use Avira on the downstairs desktop, but an error after a windows update left me unable to use it, or reinstall it. And because I don't want to keep diagnosing said problem, I just installed kaspersky, and am very happy with that.