Well i know for a fact that avira has one of the best anti-virus/anti-malware engines however not exactly sure on its system impact because the last time i used it (sometime in 2013) it slowed my system to a hault. Panda on the other hand is an anti-virus/anti-malware product that i have always loved; its light, it has a fairly decent detection rate and since they were the first anti-virus company to implement cloud security into a consumer version of their anti-virus software they've got the upper in cloud anti-virus when compared to other competators. Microsoft windows defender is pretty decent as well, its light, gives you decent security. However, if your into downloading torrents, visting risky websites and pushing you computer security to the ragged edge it would be best if you stayed away from it. It is for the more average user who'd watch netflix/youtube on their PC, check their accounts once in a while, create spreadsheets (well you get the idea).