gawd ... I wish people would think before talking cr@p
none of us knows enough to answer that question
the magazines etc will infect a machine with a known set of threats ... and then try each package in turn ...
they don't bother about cousin derek's milkman ... who knows nothing about PCs ... but always picks the grand national winner
if you want a freebie ... Avira then AVG - and they'll be borth every penny
if you are willing to pay (look for OEM versions)
read a magazine or some other trusted source
currently AVIRA is the fave
but it replaced Kaspersky (I think just because after more than two years at the top spot ... it's time to give someone else a chance)
go for a security suite if poss ... that way everything should work together