Customer: Someone who does not want to do anything or worry about their security. Someone who wants amazing security. And doesn't want their system resources eaten up.
So, in other words, a customer who wants the whole world but doesn't want to lift a finger to have it. (I've gotten this quite frequently.)
Reality: there is no such thing as "worry-free" security. Get that thought out of her head. Any hint of "worry-free" security will translate to "anything goes; I don't have to worry" and guess who will be on the hook when her computer is riddled with malware?
Locking your doors doesn't make your house, car impenetrable and neither does the best security setup in the universe.
Having said that, I'm not insensitive to users who don't want to bother with security and I don't want to be bothered by a question every time a prompt comes up on their computer.
A long time ago, avast! was my go-to free av for this but it got naggy and chicken little-like (too many false-positives, like trying to compete wth Qihoo or something), so that's out.
So, for free, I'd have to say Bitdefender. I don't say "Panda Free" because I've just started using it and am having problems with it.
For paid, Kaspersky.
Then VirtusTotal uploader (for if you get asked, "is this a virus?"), Chrome + uBlock Origin extension + WoT extension (only one I've found that flags the popular fake login sites) and maybe SpywareBlaster (if you're going to keep it updated) and OpenDNS with the updater and some options (like adware) enabled.
Of course, scan the sh-tuffing out of the computer first (Emsisoft EEK, AdwCleaner, Stinger, Malwarebytes, Zemana).