You probably haven't come across Sophos antivirus, because it's enterprise software, which means the company's target consumers are small- to large-scale organizations instead of home users.
I'm generally against 'elitist' software like these, but Sophos seems to have a loyal customer base so I thought it deserved a review. I've been using Sophos for almost six months now; I don't like it, and the only reason I still have it is because my university gives me a free copy. Read the rest on AV Scan