Hmm... Let me see now. How to put this most succinctly.
AIS 5 is not perfect but I find its various weaponry intelligently coordinated in such a way as to be highly effective while causing minimal impedence to my computing experience.
CIS 4.1 Premium also has many effective anti-malware weapons... but not much of a brain!
In its contribution to the serenity of your PC use, you will find it is as much an enemy as an ally.
It's also no longer as "light" on resource use as it once was. E.g. in one recent test, AIS increased the time taken to execute Open Office 'swriter.exe' by 47%. CIS increased it by 180%. Of course, that's after you have on previous occasions dismissed a series of Defense+ popup warnings because CIS "Default Deny" policy does not trust the vendor.