There is not one AV that is Perfect, Mate, each has their Problems.
I work on a lot of Computers for disadvantaged people that have little money, so use Free Programs where I can, as a contributation towards them. Like here, I don't get Paid for my time, I just do it for the satisfaction of helping those less fortunate than me.
What I mainly use are as following, but not all are just AV? I have found that a Blend of different Programs lead to few call backs.
AntiVirus installed, used and upgraded daily, is AVG Free, now 9.0. Link here. http://free.avg.com/us-en/download?prd=afg
Go for the one on the left.
AntiVirus used as a Back up each Month Online, just to be sure is Kapersky Online Scanner 7.0 Link here. http://www.kaspersky.com/kos/english/langu...176479253112345
AntiMalware installed, updated when used, MalwareBytes Anti Malware. Link here. http://www.malwarebytes.org/mbam.php
AntiMalware installed, updated weekly, also has Tea Timer that advises you if something is trying to change your Registry, SpyBot S&D. You can Donate to them if you are Happy. Link here. http://www.safer-networking.org/en/home/index.html
General Watchdog. Sits quitely in the Background and monitors your Machine's various parts of it's System, correcting those it finds after clearing it with you. I must add that the Defagment feature is really unreal, HDD is always Perfect.Many other Utilities available. Advanced System Care Free. Link here. http://download.cnet.com/Advanced-SystemCa...4-11043531.html
All of the above are Free and work really well. They save me so many call backs. There are other Programs much more better techniqually, but my Clients would rather me take care of any Problems that arise.