In my opinion ESET NOD32 is the best, I've used it for years and never had any problems regarding security.
Its not security that matters but privacy, and in some cases it's the same.
Instead of giving your credit card info and bank password so some thief in a 3rld world country ,now you give it to spies from your gov.
I was just thinking the same the other day but if you're on a windows machine then you have no choice but to rely on one of these antiviruses otherwise it'll get infected pretty quickly and there aren't much choices with open source antiviruses. I know one that is ClamAV but I don't think it will work as good as the other ones does.
And it's hard to only run a linux system as some of the apps don't work on it too great.
kaspersky antivirus is best i think!.if we are using an antivirus we should look the whole system of it ,that is preferable to our needs and the best.. 
