I have a completely different experience with the free av's.
Panda Free is usually one of the lightest, but according to the HUB also on protection
Hate it's toolbar (can be uninstalled to keep web-protection). Adds an annoying extension that wants to change your search-engine.
Second lightest is Bitdefender Free. Had no problems with it on any of the systems of my family members where I installed it.
A true set and forget solution.
But recently my mother in law noticed that the certificate of here banking site was different.
So they now perform a kind of MITM attack for HTTPS scanning.
That's a problem for her because the address bar of IE is no longer green and therefore she didn't feel safe anymore to do online banking.
So my preferred free av is now Kaspersky Free Antivirus where you can exclude EV certificates from HTTPS scanning and my mother in law's problem is solved. KFA is doing great in the HUB and in my personal testing. No bloat and no bugs anymore (Chrome SSL certificate problem is solved by Google). Also because of GDPR you can turn off all marketing.
Kaspersky Cloud Free has some bloat and a bug with firewall settings in windows defender security center.
That's why I prefer KFA above KCF.
No recent experience with Avira Free because of it's launcher, ads and the use of Mixpanel for analytics in their extension.
No recent experience with Avast and or AVG because of ads and shady marketing and telemetry.
EDIT: So you should always try them yourself to see if you like them and if they work on your system.
It seems everybody can have a different experience with the same av's due to different hardware and/or software configs and personal preferences.