On Roche's path, you eventually get the choice to rescue the little girl, or Triss. Rescuing the girl leads to another choice - turn her over to the king, or to the reagent. That determines who ends up ruling Temeria.
So what happens to Triss if I rescue the little girl? If I rescue Triss instead, what happens to the little girl (and Temeria)?
Triss is saved either way, but if you go after her instead of saving Anais you'll have the pleasure of personally slaughtering the Nilfgaardian delegation, which has some ramifications on the meeting and may possibly have an effect on the next game.
If you save Anais, Dethmold's dead, and Letho, led in by the Nilfgaardians, claims that the Lodge of Sorceresses was responsible for the assassinations. What follows is that 99% of the mages present are slaughtered; the Conclave is not reformed, and there is no normalized relations between the kingdoms. In other words, the Nordlings are ripe for Nilfgaardian conquest.
If you save Triss, she implicates Sile. While there is some violence towards mages, it is minor. The Conclave is reformed, including the diplomatic connection of the kingdoms. The North is somewhat united, with fireball backup, to face the coming Nilfgaardian invasion.
Also, Roche does save Anais if you go after Triss. Dethmold escapes, and Roche is declared an outlaw, but Anais is probably safer in his care than anywhere else. Given all of that, I actually think the Triss ending is the best one on the Roche path. I'm having trouble deciding which path I prefer on Iorveth's path, though.
You should have gone with Roche to murder Dethmold, then give Anias to Natalis. The sorceresses are no good and deserve to be slaughtered. In their scheming they enabled the Nifgardian spies to infiltrate the kingdom and allowed the murder of 3 kings.
Iorveth's path is pretty clear choice: save Saskia. You fought for Vergen's freedom already so why not save their leader too? Besides, you don't want a dragon around vying for vengeance.