I've played through it once so far. I completed Roche's path which was filled with many decisions that are sure to impact the witcher III. I'm curious what were other people choose and why?
Here were my choices:
1. Aryan La Valette
I convinced him to surrender and saved him in the dungeon mostly because he seemed a reasonable enough chap.
2. Roche or Iorveth
It seemed illogical to go with Iorveth given Roche and I were on good terms at this point so I went with Roche. Although I was true to my word with Iorveth when we encountered Letho and handed him his sword.
3. Henselt--Live or Die
I let him live given that killing him would only serve the Kingslayer's aims which we had been fighting against up to that point.
4. Roche (Anais) or Triss
I choose Triss. She was the main reason I went to Loc Muinne.
5. Sile de Tansarville
I let the her die in the portal. She got what she deserved!
I put it out of its misery.
I really wanted to fight this guy but I let him go because he really wasn't my enemy, he never harmed Triss or any of my other friends, and he was a fellow witcher. Will definetly fight him when I do Iorveth's path (which will be a 'non-canon' playthrough if you will).