The av-comparatives test only tests the paid for versions of AVs.
Nonsense. The good ones test both free and paid on the same AV (e.g Microsoft Security Essentials gets tested against the paid AV vendors).
Three words for you .... quality not quantity.
So, I'm using the free one, and feel pretty protected, having not had malware for at least three years.
Sure, and it's equally possible not to have malware for years if you don't run any AV, take a suitably cautious approach to your computing and wave a dead chicken over your computer once a month.
However because your average home user doesn't understand the importance of not running as admin, being careful with attachments etc. etc. then they need a form of AV and so yes, I guess a freebie is a case of "something is better than nothing".
As I said before, I'm not saying all the free vendors are rubbish .... I'm saying that the quality varies greatley and that even the best are not rated as highly as the best commercial ones.