Still tooling with the Paladin trying to find a good niche for him. One time I did play him I was never able to get enough Valor to pull off an Aura, until I could not spare the Quick Action to do it (was using my light saber to melt face). He may work with some buddies, using his banner in far away place to get two bodies on the field quick. Holy has some of the better creatures out there, just most are over his starting Channel (this is how I judge usefulness, it does not rule out a creature though).
The Siren, while cool, keeps running into problems of solid creature pool. Water just does not have a very large depth of creatures to pull from just yet, and I am not sure she can do the Buddy build style very well. She has some very good control, and can play the push game like no bodies business. I have seen her just wreck with Tsunami as well, he spell pool is top of the line amazing.
My thought on first use, and build play.