I always have a soft spot for avast.
Honestly, I can't find any physically stronger, lighter, novice user-friendly, free AV than avast with my tweaks
I ran it in 1 of my business PCs and let everyone did what they wanted to do (all novice users). There had been zero infection for years, thanks to the combo of HM aggressive and syshardener
I upgraded that machine to Windows 8.1 (noticeably faster than windows 7) and installed Kaspersky Free (tweaked for max. performance) + syshardener. This has been running well, too. However, this combo can be bypassed by the same method in the videos.