The problem with most of the big boys is that they get to a point where they become a victim of their own success:
1) Tech support inquires take a week to get an "autobot" response". If you start the e-mail with .. "This is what I have already checked, you get an e-mail telling you to do what you already did and told them about a week ago,
2. Their paranoia results in DRM / license maintenance issues that become overly burdensome.
We used BitDefender on multiple sites last year and had a fair amount of issues ...
a) Doesn't like old files
b) Very onerous to shut off for troubleshooting purposes
c) Support takes forever
d) For 2015, I downloaded it one to a thumb drive and did installs at each site from the thumb drive. The 2016 requires the program to be downloaded to each site / machine and I just don't have the time for that.
We have been testing Kapersky Suite, both get consistently high marks on the test sites. But no file access issues, not disabling / troubleshooting issues and most important .. easy ownership and license maintenance.