I used SecureAge's SecureAPlus for a year, and was quite impressed....; I'd have kept using it but the 1 year trial expired...
Works on a 'whitelist' principle everything you list as good zips along, and it tends to ask for your permission for new things, and, blocks known bad things....but will allow you to override anything if desired.....
Uses few resources, taps into 13 cloud engines, etc....
I saw no negatives at all, in fact....
(Although some folks don't like being asked "Allow or Block', I think it's preferable to just automatically blocking or allowing, personally..