I was able to have Leliana as Divine in a playthrough were I allied with the Templars and I saved Celene and reunited her with Briala.
Of course, the Mages were innocent, just Fiona was a "little" stupid to side with Alexius. I'm just thinking that in the long term point of view, conscription seems a better choice. These are the lines you get in the epilogue if you conscribe the Mages (from http://dragonage.wik...e_(Inquisition) )
Cassandra is Divine
In the end, they accept Cassandra's invitation to rejoin the Circle of Magi, but as a new college called the Bright Hand.
It is not long before this new college dominates, pushing for reform and close ties to the Inquisition.
Rumors begin to circulate of a split within the Circle, a shadow war against the new college by unknown forces.
Leliana is Divine
When Leliana disbands the Circles, they remain with the Inquisition and form a new college called the Bright Hand.
To many, this new order represents the best of mages, an example for the rest of Thedas to follow.
Vivienne is Divine
In the end, they elect to leave the Inquisition and refuse Vivienne's demand that they join the reformed Circle of Magi.
However, this new mage rebellion does not last, as the Divine brings down her fury upon them.
Some mages surrender; others return to the Inquisition. Either way, the new Circle of Magi stands triumphant.
while these are the lines you get if you ally with them:
Cassandra is Divine
In the end, they refuse Cassandra's invitation to rejoin the Circle of Magi and instead reform the College of Enchanters as a new order.
The College, they say will allow mages of the South to gather in peace and seek new solutions to age-old problems.
From the beginning, the College and the Circle have clashed – and some fear it will lead to a new war of the mages upon themselves.
Leliana is Divine
When Leliana disbands the Circles, they leave the Inquisition and reform the College of Enchanters as a new order.
The College, they say will allow mages of the South to gather in peace and seek new solutions to age-old problems.
For the moment, it appears to be working – mages are enjoying unprecedented acceptance throughout Thedas.
Vivienne is Divine
In the end, they refuse Vivienne's invitation to rejoin the Circle of Magi and instead reform the College of Enchanters as a new order.
The reaction from the new Divine is instantaneous: a war to dissolve the College before it begins.
Some mages surrender; others return to the Inquisition. Either way, the new Circle of Magi stands triumphant.
So, it seems that if you side with Mages (alliance or conscription), Leliana is the best choice as Divine, while Cassandra leads to a new war. Vivienne destroys any kind of rebellion in both cases, so she's the worst choice as Divine.