maybe it is a trick question..........
if you give the wrong answer you are banned from the forum for 3 years......
LOL!!!!
p.s., my Opinion is that if you want free AV, avast just offer more features in compare to free AV, even that Avira free has way a better protection, also their update servers have improved with more bandwidth recently.
About a paid product, I will stick with Avira Premium Security Suite. (Sorry avast fans!)
These days some AV vendors are doing everything else than being Detecting malwares, it's a sad story.
Antivirus, as its name says should be Anti-virus, if antivirus don't detect malware who cares how good looking it is? how light or heavy it is? how many guard it has, how light its update is? what would be benefits of them!
So to choose an AV first you should choose an Antivirus that can detect highest rate of malware with minimum FPs and then think about how it can prevent those detected malwares come into your computer (how its guard works).