Antivirus software feedback and opinion

This thread is Virus Threat Center’s official antivirus software feedback and opinion thread. This is your space to discuss the good, the bad, and the ugly of AV software.

Which products do you believe are the best and why? Which products do you believe are the worst and why?

I have just one request. Back up your opinions with fact!

Don’t rant about how you hate company X because they are secretly releasing viruses only to prop up AV software sales–unless you have definitive proof. Don’t complain that product X crashed your system without sharing the details.

That said, let the discussion begin!