The best antivirus/ security suite is often a subjective matter: in reality, there are some aspects that should never be underestimated when choosing these software : 1) Protect the system in background taking the minimum of resources (and thus avoiding to slow down the activity of the user). 2) Not only use a database of virus signatures to detect threats. 3) Make use of behavioral analysis in order to promptly block all those threats that were not yet known. 4) Support, possibly, the use of algorithms of "collective intelligence" by cloud to detect threats just appeared in the network and, therefore, with good probability, unknown at the moment. 5) Reduce to a minimum the false positives. 6) Indicate to the user the software and the extensions to be updated to avoid any vulnerability can be exploited by cyber criminals to attack the system in use.