Absolutely right ignys!
When chosing an antivius we don't have to look just at the features and at the resources used.
It is EXTREMELY important for an antivirus to be well spread in the world!! THe antivirus must be popular!! WHY?
Because the signatures for the viruses are built upon Customer's infections and their submissions to their Security Responses.
If the antivirus company don't receive the virus or infected file, they cannot build the definitions...
If you chose companies like McAfee, ESET and Symantec you are much probable to have the antivirus updated for the more recent viruses, but if you use the super antivirus "hhiuuus" few people in the world are using it, so the company makind its signatures is not aware about the new virus and it doesn't detect it!