I use Avast , I have also got superantispyware and Malwarebytes. I recently changed to Comodo firewall which seems fine and I seem to boot up quicker. They are all free for personal use and I have had no trouble with Viruses Trojans Hackers etc. I also use Windows Defender from the Microsoft site.
From those that are in the pool i chose kaspersky. I used AVG and it is not to good. I think that the best antivirus are bitdifender total security and zone alarm a great firewall. But also i recommend to all Eset Nod 32. This ia a great anti virus too and also keep your system up to grade.