in no particular order
notice how most of them start with an A
norton is the fastest and most pc demanding of them all, but i have a specific personal list of anti-viruses that people with viruses use.
order of severity: 1 extremely common, 2 common, 3 rare
i have fixed about a hundret pc's over the last 8 years, and those antiviruses are the only ones i meet on BADLY infected pc's
i personally use AVG, although i fancy avira as it seems to be the best one yet.
lets say the average client wants a pc that never (almost) gets any viruses, also he wants to experience a calm usage, and so that the antivirus stays "invisible" while doing what it does.
so that the user can experience the full potential of the pc without any additional headaches or viruses.
dislikes: norton is amazingly badly made, bugs every you for every little thing, takes ages to scan, blocks normal user activity, slows down the pc, and makes life as miserable as possible, as if i want to own a pc just for the sake of keeping viruses out and nothing more.
likes: finds all viruses. (if you have paid the $$$)
nod32: i don't like the interface.
mcafee: no so good against viruses
kaspersky: annoyance not as bad as norton, but also has lower degree of real threats found.
Panda: not recommended, why pay so much for so little.
in real life you don't even need a antivirus to stay safe from viruses, but its there, and its there to help, not annoy, and not to suck money away from your pockets.
the free ones are just as good as the paid ones in terms of virus protections, everything else can be solved using common sence.
do not download fun.exe from suspicious sites
do not download any .exe from suspitios sites (if you don't know what this is then enable your extensions)
do not open spam mail, and so forth.
doing some of the above can and will infect ANY pc with any antivirus (if the virus is new enough)
so why should YOU pay for something you don't need.
and why should it hider your everyday activities?
get avira, or avg, or nod32
get ad-aware or spybot search and destroy.
and a registry cleaner, like ccleaner
and type msconfig in start>run (or ccleaner) to remove as many autostart programs as possible (including some viruses and malware) only keep the necessary
note: all of above is free for personal use
and what do you get?
you get a close to free-of-viruses lifetime for free, much better than just one program!
this is just personal experience