Antivirus questions pop up frequently and you'll get as many opinions as you do comments... there is no consensus in my experience... other than... to some extent... a consensus that Symantec stinks worse than most or it doesn't. I believe it does.
That said...
You need to understand that in MOST cases, you cannot stop threats that have not been seen by the A/V vendor. You will never be satisfied with any product you get because frankly, they all stink. The one I've been recommending and using at various clients is Sunbelt Software's VIPRE Enterprise. It's a fairly inexpensive product with a good deployment and management console. In places I've installed it, comments have GENERALLY been that it has caught things that their prior products missed (including tools like AVG and Malware bytes). BUT, that said, it is far from perfect. There is nothing that gets 100% anymore... there's nothing that gets 90% anymore. In general, most products protect you from about 80% of the bad stuff out there. Maybe product x does 78% and product y does 82% but in general, don't expect better than 80%. If you have a time machine and want to go back to 1995, then yes, most products caught 95-99%. Not today.
A good security configuration will see appropriate firewall rules, user account privilages, multiple protection points (meaning your firewall/router will also be a virus scanner and will use a different engine than the one used by your computers/workstations/servers.
It's a losing battle... understand this, be smart, and you'll be reasonably protected.... but not perfectly... perfectly doesn't exist.
