Panda Free Antivirus 2015, Bitdefender Antivirus Free Edition, Malwarebytes Anti-Exploit Free and Ad-Aware Free Antivirus+ 11 are all good free antivirus options. Panda Free Antivirus 2015 includes bonus features and gets high scores from independent labs.
Panda Free Antivirus 2015 received scores comparable to those received by quality commercial antivirus tools. It's easy to use and quick to install and almost received the best possible score in malicious URL-blocking and malware-blocking tests. Bitdefender Antivirus Free Edition works completely in the background. It received great results from independent testing and it provides excellent phishing protection. Malwarebytes Anti-Exploit Free guards Java and browsers against exploits.