Samara vs Morinth, benefits of each choice?

What I'm asking here is which Asari provides the greater access to content, the best war assets, possible romance options, etc.

I know that Morinth will be turned into a Banshee if you choose to kill Samara during her loyalty mission, but as I have never killed Samara I'm unsure on the rest of the details. Does this mean that she won't appear at all during Mass Effect 3 until the end, at which point she is already a Banshee? Does this prevent her from appearing in any of the additional DLC for Mass Effect 3?

I am presuming that due to Morinth being Ardat-Yakshi that any attempts to pursue a relationship with her will result in orgasmic death.

Are there any other content or gameplay bonuses to choosing one over the other?

Solution 1:

Picking Morinth over Samara will give you the Dominate bonus power. Picking Samara will give you access to Reave.

Additionally, after the suicide mission, Shepard can take Morinth up on her offer, which does result in a game over.

Solution 2:

If you are planning to continue onwards to ME3, I recommend Samara over Morinth for some small story elements.

Samara will also provide some war assets while Morinth will not show up at all (not even in the Citadel DLC) and provide nothing outside of that Banshee fight.