I use avira for my windows 8.
Perhaps because MS has a poor track record when it comes to her own generic applications that are bundled with the OS: Internet Explorer, PAINT, Disk Defrag, Defender, etc.
I was using Microsoft Security Essentials with my windows 7, but it started to take forever to update over my high speed connection, and had no other features embedded with it. I now use Zonealarm, which covers my firewall better,protects my personal information, and lets me know if a download is safe before I download it, etc. ...and it honestly automatically updates. I always had to manually update MSE, there was always an update pending. I was going to get windows 8, but the update advisor said i needed a new computer for it, I have a Dell Dimension 8400 in perfect condition for windows 7, at least. "If it ain't broke, don't fix it."
I use Avast, not a resource hog, updates daily and good user interface. Also Zone Alarm and Trend Micro. No heavy resource hogs in this bunch. Stopped using Norton, McAfee a long time ago.