How to choose best antivirus?

How to choose best antivirus for you?

Further guidance in choosing Free Antivirus.

Credibility Can be checked with a number of the download.
A quick update. Because the virus is constantly updated anti-virus programs are good as well, so it should be updated regularly, at least 1-2 days and should be updated at least once a week.
It is Freeware Shareware Freeware chose not to use it for free indefinitely.
The program should be able to update the new version automatically.
The program should be able to set the time automatically or Scan Scan with.
And the basic need to be able to Scan and remove virus with the new.