I too used to use Symantec exclusively then I started switching to Trend. Liked Trend's SMB products very much. When I changed jobs and had to look at a antivirus solution for almost 2000 stations and servers, I ended up with AVG after evaluating Trend, McAfee, Kaspersky, and AVG. Never had used AVG much before and liked it's client footprint compared to the others, it's control granularity from the admin console, and it's price(AVG, in our situation, turned out to be half the cost of the others).
Also, Symantec, McAfee, Trend, and some of the others have licensing models that kind of suck. When I was looking to protect an Exchange server for 500 users out of my 2000, Symantec's model would have dictated I had to have purchased to cover the entire 2000 users with "Exchange" protection. McAfee was the same way and I believe Trend also was the same. Computer Associates would have been by far the cheapest because their model just needed one server license to cover the one Exchange server. So in essense, I could have gotten my Exchange server covered for about $100.00(list price) no matter if I had 5 or 500 users. I did, however, decide to keep everything AVG. AVG just licensed it's email protection for the amount of users I needed (didn't have to license my entire 2000 users for th 500 I needed covered for email).