i have been using Immunet since a very long time and this have solved all my problems. This antivirus is very fast in detecting and eliminating the viruses and is also very light, thereby balancing the internet speed.
I use Microsoft Security Essentials and Malwarebytes Pro at the same time. Both work great
Kaspersky Internet Security for the win .
I use Super Anti Spyware.
I hate Norton and those "big" commercial ones.
You can give Kaspersky a try. It's usually always updating and its pretty good. Or maybe Avira.
The best free one is Microsoft Security Essentials.
The best paid one is probably Malwarebytes Pro.
I would say Kaspersky or Malewarebytes, without a doubt because I have tested my RAT's on them and they are the only ones who detect it.
Microsoft Security Essentials is ok for many people, but if you're really paranoid, go with Avast.
I would say the best one is Norton and/or comodo.