For me I have to go with:
1- the opening scene in white orchard with Geralt talking to Vesimir buy the camp fire light.
2- Geralt walking into the dwarfs cabin on the Isle of mists to find Ciri
3- the closing scene one the "bad ending" with Geralt setting there head in hands as the camera pans out leaving you speechless...
I went with these three because mixed with the scene and the sounds and overall feeling of emotions!
Every time I here the theme of white Orchard I get that same feeling as the first time I watched that cut scene.. little did I k is my life wouldn't be the same!
The Isil just had this feeling about it, and then the scene that followed was so powerful an emotional roller coaster.
And with the "bad ending" even though I never got this one I watched it on YouTube and the gut wrenching feeling I got I can't shake it to this day.