Hi Julian, good to see you back here
I am of the opinion that most third party AVs are basically a protection racket, based on escalating users' fear. They all seem to have embarked on "an arms race" to add as many features as possible to their security suites to convince users of their efficacy. I think that I have seen more issues caused by third party AVs in friends' and relatives' machines than viruses or malicious software, regardless if these are free or paid for solutions. The business model relies on user inertia and auto renewal.
I know that the plural of anecdote is not evidence, but.... I still use XP, an old version of Avast (free) with just the File Shield and Sandboxie...I have never been infected, no viruses, malware, PUP nor toolbar....Just saying