Replying to Armada AR7 vs. K2 Revival

First off, a little about myself.
5'11'' and growing
15 years old
165 pounds
Advanced groomed skier
Intermediate powder skier
n00bie park skier

I am torn between the AR7s and the revivals. I know that the AR7s are not symmetrical, and the revivals are. I am planning on learning to switch ride once I get one of these, and am wondering which one would be best for learning that. Also, which one of the two would handle powder better? Being in Colorado, I get lots of powder. I'm not really worried about groomers, and I think that I will be mounting both at true center so that I can learn my way around the park better.

Lastly, I was wondering what size to get.
AR7s: 181,176,171,166,161
Revivals:159, 164, 169, 174, 179

Thanks so much guys!

(and it seems to help when I put +K so whoever helps gets karma!!)