I use Kompakt most but mainly because it is my solution for software drums. All the samples are high quality and fit well into my recordings but mainly I like the acoustic drum kit over any of the others I've heard and used.
The drumkits are mapped out and velocity layered for real-time effect and I can create 8 different channels for each drum part all in one instrument with 8 stereo outputs. This makes creating and editing drums allot easier! Kompakt does allow you to change filters, envelopes, add built-in efxs, and eq so its great in my opinion.
You can read a post including pics of how I use Kompakt in S4
here People say the down side to Kompakt over Kontakt is it takes longer to map out samples. So if you have allot wav or aiff files you want to map out then maybe Kontakt is your better choice.
-John