You are probably going to get many varied opinions on this one because we have all had our individual experiences (both good and bad) with AV and AV companies.
I think it would be worth your while to look at sophos (www.sophos.com) and you can download their trial version for free (as you can with most AV's) Now I need to warn you - I am a reseller of this product - so do your own due dilligence!
Here is why I like it. I own a small systems integrations company and we are asked to supply, install and then provide ongoing management and support for companies that need total endpoint security. This covers small to medium enterprises.
I like sophos because it is hands down the easiest and simplest endpoint security product to deploy, update and manage centrally. Their management console makes it so easy to set policies, remove viruses adaware and spyware all in one and view network computers by status, type etc.
But probably the best feature of sophos is there phone support. The phone rang twice and the guy I spoke to had me sorted out in 2 minutes. These guys know their stuff, they are not just people paid to read a script and then tell you they will send someone out tomorrow. Not bad considering that I rang him at 2am monday morning!
Ok - I will stop raving on. Needless to say, make sure that sophos is on your list of AV providers to check out.
Brad