AVG is now a rebrand version of Avast with Zen, a different setting UI and a lack of Hardened Mode. They are identical in all other aspects
I want to add something:
- Panda: extremely/unbearably slow scanning speed, relatively low detection rate, heavily depends on the cloud
- Norton: Automatic actions after a context scan without user interactions, sometimes can't remove a simple file which can be easily deleted in Windows Explorer, very slow scanning speed because it seems to submit everything to the cloud, Download insight produces so many false positives especially new safe files due to their reputations
- Avira Pro has a better cloud implementation than Avira free. More files are uploaded to Avira cloud so much high detection rate
- Avast: slow scanning speed compared to the version a few years ago, which was one of the fastest I have ever seen
- ESET: not so good zero-day prevention, HIPS needs to be properly configured in order to work. Otherwise, poor
- Qihoo: delayed signatures, questionable against non-ransomware malwares. I have seen it missing so many malwares with high VT detection ratios
- Microsoft: slow scanning speed, detection rate varies, impacts system performance in unpredicted fashions