7 Best USB Antivirus for Virus-free Flash Drives - Windows Report After running some tests, we have found the following to be the best antiviruses for USB flash drives: ESET Antivirus - Most popular choice. Avast Free Antivirus - Features a DND mode. Avira - Free comprehensive security. Bitdefender - Complete antivirus package. Panda - Best for FAT and FAT32 USB drives.