variety per device
I would use multiple Anti-virus programs and other programs on each of the same type of device, eg 3 PCs then at least two AV programs so not all are caught by a single instance infection. AND it should be different to the AV used by your ISP . (For example my ISP BT internet uses and offers McAfee , so the some machines are McAfee while one is not). Problem is roaming, the tablets and phones can pick up anything outside your network. The key of no adds is well put but that would restrict the add revenue to some legitimate sites that need it to pay bills. I would treat it as a three ship problem , each ship (device type) being handled separately. No one solution fits all. However this is a market you have spotted and no vendor is as yet moving to support it
Biting the hand that feeds IT
