I can see why this one's your favorite. It looks like you stylized it to your own interest, and I like it, actually! :L
...Yeah, it's all awesome, the background, the Regice, everything. Though I think, Regice has icicles coming out of its back. I'm not sure if you forgot or left them out of perspective, but either way, still great.
You have unbelievable talent with these drawings! You truly captured every last detail of the Regis, and even added a beautiful background to make it even better. You managed to make it look so realistic and cool, especially with the perfectly added shading. Your drawings are amazing, and for all of that, I applaud you.