Actually, almost all antivirus are best as long as you keep them updated. Even with the most popular antivirus installed can still be penetrated with a virus if users aren't careful.
For a free version, I like Free Avira and for paid version I always use NOD32. It's a matter of preference, really. Some people like Norton, Kaspersky or Avast.
Also, for added protection against malwares which cannot be detected by any antivirus, install softwares like Malwarebytes or Spybot. Malwarebytes has free and paid version, paid version allows real-time protection and can be a good complement with the antivirus.