AVG. I've learned from personal experiences that McAfee is horrible. It has horrible detection rates to start of with. Within the first week of getting my new computer (pre-installed with McAfee), I got a fake anti-virus and I had to clean it up myself. Then it doesn't have a behavior blocker that I can see. A behavior blocker is a must in an IS and it doesn't have one :?.
McAfee has also been blocking legitimate programs on my PC.
McAfee is horrible.