avast / avg / bitdefender = all free
though my memory of test results are old, this is what i recall:
detection: bitdefender > avast > avg
package (everything other than the av itself): avg > avast > bitdefender
ease of use without friggin ads: avast > bitdefender > avg
i use avast. i maybe bias, but it dont spam me like avg, and i find it has a lot more to offer than bitdefender.