for free av kaspersky security cloud free ( if configured correctly that is ) or defender with andy ful configure defender at high settings. I use eset internet security at the moment , I was lucky to get a 3 year license for free from someone over at the " other " forum.
I prefer Avast because of its Hardened Mode, it's better than Kaspersky's Application Control, but the decisive factor is that Kaspersky doesn't offer their Application Control module in the free version.
Free for me is Windows Defender with Config Defender set at High. Other than that, the only other AV I think I'd consider right now is Wise Vector Stop X. Tests of WV I've been seeing are pretty impressive.
Ha-ha! I just changed my vote to WD after using WiseVector for awhile. I like both but prefer built-in,
AVG not avast - UI related choice - IDP is waaay better implemented in AVG (probably because it`s their BB technology)