I'm a programmer and have spoken with several co-workers on this topic, including the security folks at my company. I was a die hard Norton subscriber for years. I was talked into using AVG (free-ware) a few years ago and have not had a problem since. Virus free for about 2 or 3 years now. I also run on occasion, Spybot and Ad-Aware every 2 or so months to be on the safe side.
My husband is a computer technician and is in school for computer software/programming at the moment and will be getting his master's in computer security so we go through all sorts of anti-virus software. We've used Mcafee, kaspersky, norton, spybot search and destroy, advast, malwarebytes, superantispyware, at one point or another. He's always on the lookout for a good one. We usually install maleware bytes and superantispyware free versions when we're fixing computers for customers that bring us computers that have virus' on it.