We've long been fans of avast! around here. From the antivirus functionality itself to the brilliant anti-theft features with root support, it's one of the absolute best security apps on the Store today – and it keeps getting better. Take the most recent update, for example.
At this point, avast! is already working with a great app, so the most recent additions have been about streamlining. Simplifying. Taking the good and making it great.