I use Norton

 

Avast

 

Linux. :p
(Well, at least on my laptop.)

 

As long as you use mac or Linux, you're pretty safe. I do use avast on my windows vista.

 

I use Windows Defender and Malware Bytes. I just run the scans every few weeks.

 

Windows Defender. I pay attention to what I download and install, so there's not really much of a need for a robust anti-virus anyway.

 

Same, Windows Defender, Malware Bytes, and Linux on my laptop.

 

Mac is pretty good at filtering viruses too I think.