I agree with Lewis, I also don't like the aggressive marketing tactics of Norton and McAfee.
As important as anti-virus IMO is a good firewall. I've used Comodo for years and am very happy with it.
After all, it's better to stop malware entering in the first place. I use MSE for scans and also have had no problems with it.
My vote goes to Comodo too. It offers full security suite for free. It is a bit poweruser'ish, but really offers a lot like sandbox and really configurable firewall. CIS's antivirus has pretty good heuristic engine, but it may sometimes give a false warning. It happens really not too often (like some reviews may say) and you learn to recognize them. At least I don't get annoyed with it.
Comodo is a top notch firewall. It's AV is good, mainly because it is a poor removal tool, but a good blocker (removal comes with payware version). Especially some older reviews give poor results for Comodo tools, but for example Comodo was top performer in Matousec's proactive challenge in 2011 and 2012.
Year ago I ran Avast as my AV and Comodo as Firewall, but after my last OS install I went strictly to Comodo and like it so far. It is by far the best package for the price (free
), but I still may go with Pro version some day, which costs only 5 bucks a year!