I have used AVG, Avira and Avast. AVG used to be good but I've noticed that it deletes some files without confirmation. Also, I could not get how to configure certain options. It started behaving erratically after sometime.
Avira is good but sometimes, it will pop up an ad that seems like an infection itself

. But, it's a good product nonetheless.
I found Avast slightly better than Avira. My system crashed however and I wasn't able to do a full evaluation. (I am now back to Avira as I restored an Acronis image of a Windows + essential apps install in an amazing 15 mins.)
I would rate them as Avast > Avira > Avg.