I must say, #1 reminds me of @IcedEarth's entry in one of the previous SOTW comps. It's quite awesome (slight shame about the quality, but no biggy) and I am quite envious of the skills involved to produce it. I assume it was done with Adobe After Effects (please whoever made it, DON'T say yes or no yet for obvious reasons). So this one gets my vote. The Normal/Mutant contrast really captures the theme well IMO.
I also liked #4 for the crisp and clear signature. The snow really makes it stand out from the others, but as @Stuck said, I feel the Summer side should've had an animation of its own (maybe a few animated rays of sunlight shining through the tree or something, but not 100% necessary).
Good job to all who entered, they have all captured the theme well in one way or another. Well done and good luck!