AntiVir and Avast will let us run a quick, full and customized scan while AVG will only allow us to run a full system scan or custom scan. Running a quick scan is what many people would like to use because it does not make sense to run a full system scan on daily basis especially if the real-time monitoring against malware is active all the time and if we would like only to check if the new and updated definitions can find malware in the active processes or critical areas in Windows.
Note that the Fast scan in AVG is not a quick scan rather the memory usage to use by AVG. Choosing fast scanning in AVG will use more memory but will finish the full system scan faster than normal scan time.
All of these 3 antivirus programs will let you right-click a file, folder or drive to run a scan. Note that only AntiVir and Avast are offering boot records scanning.
Like some other antivirus program, AntiVir, Avast and AVG will not scan all file extensions by default which means you need change the default settings to scan all file types or extensions so that malware that will hide their extension or duplicate the extension will not be overlooked by any scanner.
