The free anti-virus programs keep getting better

For the past several years, I recommended AVG, it was free and effective.  My only issue with it was the continual nagging to upgrade to the paid version.  It was not required, just lightly and continually suggested to the point of being irritating.  As such, I moved on and suggested Microsoft Security Essentials.  It had my key features, primarily being free, amongst also being effective.  The biggest feature that it had over AVG was that it did not bother you to upgrade to anything.  It sat quietly in your system tray, so quietly in fact that I often got calls from customers asking if they had an anti-virus program on their system.  Being bored with MSE, I looked for another option.  I had a feeling that there maybe something better out there that was free.  Many tech professionals never get virus infection because we tend to know what to do and not do.  However, in my case I need to use one just to keep up with all the customers I have that DO need an antivirus.  I need to know what is good and does not nag.  I moved on to Ad Aware Antivirus security suite.  I read many outstanding reviews that indicated that it was a great anti-virus program.  I agree, it does occasionally ask about upgrading, but nothing like AVG did.  Well, it seems like I am coming full circle, the new reviews of AVG 2012 Free are outstanding and maybe it may be a time to give it another try.  Whichever you choose, it is nice to know that most of the free options are good options.