One man's trash is another man's treasure.
This certainly applies to AV and firewall programs. The subject has been discussed here and on other websites to the point of: ad infinitum, ad nauseum.
Thrax has posted on this site previously, several times actually, the results from an independent organization called:
AV-Comparatives.org
Go there and read the results and data. See how they do what they do.
BTW, I am now using
G DATA Internet Security. It's top-rated at AV Comparatives and a year subscription is $29.95 USD.