If you monitor this forum for any length of time you will find out that the "AS" (Anti-stress) seems to be preferred over the QA model.
Why don't you run a survey?
I have both the P99c/AS and the full size P99/AS and both are the absolute best pistols I've ever owned.. (And I've gone thru a pile).
I was raised on traditional DA/SA's pistols and my only descent into the QA type trigger firearm was the Glock 26.. I had two of those several years ago, and I hated the blocky grip of the Glock, and the trigger action. Also, the Glocks were not as accurate (for me) as my Sig P239, which is not as accurate (for me) as either of the Walther P99's.
I find the P99's 8.8lb DA and 4.4lb SA, and 4.4lb "AS" mode to be absolutely perfect for ME.
Try and find an example of each to fire. What suits one person does not necessarily suit another.
I will tell you that the "AS" trigger/striker system is not complicated, tricky, or confusing in the least.
Here it is:
DA- just like any other pistol.. Leave the pistol uncocked and the first round, and first round only will be the heavier 8.8lb trigger pull.. I think of the DA first round as a safety in the same manner I do any of my DA revolvers.
SA-With a round in the chamber if you have the pistol cocked the first and every round thereafter will be the light 4.4lb SA pull.
"AS" (Anti-stress). This is simply a THIRD OPTIONAL trigger/striker pull, that you are welcome to ignore completely should you chose to do so..
All it means is that in DA mode if you retract the slide slightly the pistol will go from a long trigger pull 8.8lb trigger to a LONGER Travel trigger pull LIKE the DA, but about halfway back you "feel" a click and you are in the 4.4lb SA mode.
I personally see no need for the "AS" mode for my needs, so never use it. My method of cc is first round DA with all SA' rounds to follow.
The Walther P99 has a visible red "cocked" indicator that you can see in the daylight, or feel in the dark to let you know if you are in cocked, or uncocked mode.
If the AS mode confuses you, think of the P99/AS as a car with a two speed transmission. (a'la Chevy powerglide of decades past) The AS mode would be a third gear you simply never use, need, or care about.. But it is there, it comes with the package, costs nothing, so don't worry about it.
Hope this helps.. Run a survey..
Best Wishes,
J. Pomeroy