I voted sophos earlier, seems its almost always infected on malware hub, even with syshardener. Maybe it should be 100% secure option with either comodo firewall or voodooshield
I have always thought that bitdefender doesnt fit with any other software, so i would either run it as total security or go with some other antivirus
Avira performs well on tests, but havent seen it tested on malware hub or somewhere else. Avira has web extension as web filter on free version (?) so it might be light, but im not sure how many ads it has nowadays