Alrighty then, I'm on my second playthrough and intended to try and setup Giselle as Divine and found this thread. All I can say is I disagree.
It comes down to this simple point. Of the two viable and acceptable (to the game) candidates Leliana and Cassandra both come to my inquisitor for spiritual guidance when they are troubled. Who does my inquisitor go to? You got it in one, Mother Giselle.
She is more of a faith leader than a military or political one, in other words, exactly what the Chantry needs. The last thing it needs is another War Leader, Mage or Politician/Spy. The issue with the Chanttry is that it has become a political entity. This is why it was so crippled when Divine Beatrix is killed at the conclave. They were too busy politicking to take care of the people who are their charge. Mother Giselle is exactly the opposite. When the war blew up she headed into the hinterlands to assist the refugees threatened by the conflict while the rest of the Chantry was off somewhere in Orlais arguing with each other.
Leliana is an option but is she a better one? She seems too extreme in her reforms, Cass is needed elsewhere to reform the Seekers and Viv is flat out power hungry. I wouldn't let that narcissistic creature into the same room with the sunburst throne. Giselle on the Sunburst throne would have the support of both Cass and Leliana plus the Inquisition. I highly doubt anyone would be willing to face that trio of powers in a grab for power. They'd get smushed quick.