The last one I think is best, with the juxtaposition of large and smaller, "framed" portraits.
I think in general they're a little too busy and crowded, though clearly they're not just thrown together at random.
Still, the individual elements in especially the Ember and Moonshade ones don't really blend/mesh, to my eyes... I think my graphic design prof might've called them "arbitrary" - but then he was also known to make students lock themselves in the toilet and cry.
I'd say try to make more use of the shapes themselves and not just their "meanings". Letters, for example, can be interesting in their own right no matter what they mean, and similarly faces/bodies all have their interesting curves and angles and colours. All of those are graphical elements beyond what they contain - that is to say, a face isn't just a Rillfisher/Ember/... but also a shape that will "respond" to other shapes, just like notes can be combined into chords, or into disharmony (both intentionally or not).
In this cover, for example -- http://www.elfquest.com/gallery/images/siege8.jpg -- the rocks, Leetah, Skywise, Cutter, Geoki, Dart, Geoki's father all guide the eye upward into the central spire of the Palace, and the roundness of the Egg is repeated in the "healing-lights" - I don't mean to say that a strict symmetrical composition is "better", nor is this my favourite cover by any means - just the next best example I found... and since banners are rather small fiddly affairs they might benefit from some unity/clarity.
Now... I'm sorry -- this was really much more of a ramble than a direct response to your bannercraft, as I think you're already doing the "composition" thing anyway, but maybe it nonetheless made sense to someone somewhere. I guess it wasn't too informative or helpful, though. Ohwell... felt like it.