The days of nostalgic virii are long gone. Where a wizzkid (angry or not) designed a virus and unleashed it onto the community.
I believe that nowadays most virii are the works of corporate incentives to keep the online community buying updates and software.
In this regard I think that malware, spyware, virii and all malignant programs should all be designated as criminal. And prosecution, how difficult it is, should be a high priority.
As for free versus paid. I do believe that paid services will get better achievements. But will also attract criminals who will hunt for benefits.
I sincerely believe that an honest person with good health, sane mind, proper education, angelic morale and high intelligence should code programs. But of course there are tons of insecure, tainted, damaged but highly intelligent persons out there who are capable of producing excellent output in code on a paid basis. Big money attracts big crooks. You know who you are...
And I don't trust them.
So one can not ever be sure.
I've used Avira for all my family's pc's. And it suffices. Because all other commercial anti-virus will NOT actively protect against getting data from the internet with permission. Be it via messenger transference or download channels. Some say NOD32 does, as do others using heuristic detections. All I can say out of experience that I've been infected whilst running Norton2005, Norton2006, McAfee2007.
The only technique I'm thinking of is SandBoxing. But that is only possible on fast machines with decent specs. And it would require proper support from the OS as well.
As of 2008 I'm using BitDefender Suite. It does all it needs to do. Haven't been infected since. But then again, I'm experienced in surfing now and won't click on flashy banners, pop-ups etc.
Still, isn't it wonderful how much information and data there is to be enjoyed on the internet? Knowing that there are a lot of shady people running things behind the scenes...
Be sensible, be safe.