I'll say... NEITHER!
In operation ALONE Norton is one of the most obtrusive AV applications and it cannot help "waving the company flag" to remind you it's there. and it's always claiming to find something that turns out to be nothing
(Kinda like a TSA officer slamming you to the floor after finding a nail clipper in your luggage)
First a question:
are you one of those foaming-at-the-mouth anti-Microsoft clowns who was aparrently fitted at birth with a tinfoil hat two sizes too small?
If not consider Microsoft's FREE "Microsoft Security Essentials"
It has caught and removed some things that Norton and AVG didn't even detect.
It works...... it's FREE!
More importantly it doesn't give a host of false alarms like Norton does, seemingly to convince you that A) it's working and B) that you should renew your subscription.
Because MSE is FREE it doesn't waste time constantly trying to sell you on the idea of continuing to pay for it.
Lastly, unlike Norton which always seems to want to update and slow your computer at startup (even if you tell it not to) you'll hardly be aware it's there.
THE first thing I do when a customer brings me a computer afflicted with that malady generally
refered to as "the slows" is remove ALL the AntiVirus applications.
(typically they have two or more AV programs and the ones that are out of date also waste startup time trying to update before they determine that you haven't paid)
USUALLY the problem is that someone was foolishly thinking that if one AV application is good then two (Or mre) is better... Ahhhh. Not only no but "HELL NO!"
Having more than one AV applicaton is like trying to move traffic through a busy intersection by using two or more traffic cops, each of which despises the others and is trying to make them
all look bad...
It is my considered belief that whichever Anti-virus I Notice least is probably doing it's job the best
If it has to constantly advertize itself it probablt isn't as good as it claims to be and frankly? Norton
is the "poster child" for this obnoxious behavior.
Kaspersky? I have no direct experience with t but as I recall one of the staff here did a comparison
between Kaspersky and MSE and didn't find a lot of difference in performance....
Granted there was a difference but as I recall their conclusion was that the difference wasn't worth paying for.