As you've indicated, some responses might be based upon personal allegiances, rather than 'scientific reasoning'.
However there are two security suites which are generally reviled by most contributors to threads like this one. The reason has got nothing to do with personal prejudices; it's because they both have a bad reputation for being 'resource hungry' and slowing PCs down (often dramatically). Those two programs are Norton and McAfee. I certainly wouldn't have either on my PC, even if it was offered free of charge. (Some reviews though do suggest that the latest Norton products aren't anywhere near as bad as the old ones. There are actually a few people who like them, but I suspect that they're still very much in a minority).
The vast majority of people around here use a free Firewall. (Zone Alarm is the most popular but Comodo also has plenty of fans). They then add on a free anti-virus program. (AVG used to be the favourite but some people haven't liked the latest version. That's resulted in lots of people switching to Avast! Avira also has its fans). Then they top up those programs with one or more free anti-spyware programs. (AdAware and SpyBot Search & Destroy are the most popular).
The free stuff should do the job at least as well as (or probably better than) either Norton or McAfee. If you're still not convinced, and insist upon paying for a security suite, Kaspersky is widely praised by some of AB's most knowledgeable contributors.
Chris