Woot! First post.
I have a few things to say about all of them.
Picture #1: Not the greatest sky and fog, I can't see the background at all and in this case that is bad. If you are going for kinda a swamp/wasteland type look then try a dark brown fog.
Picture #2: Exceptional terrain, but you could add some more stuff to the right side of the picture. Perhaps another iceberg in the distance. Some birds in the sky would be nice as well.
Picture #3: This one is quite good but the light looking down on the Eye of Sargeras looks bad, remove it or making it green so it blends in. It looks placed poorly. I generally love this one but you need to fix the blurry vines in the front of the picture.