"Miles being more valuable" is entirely subjective and depends on how you're going to earn and use the miles. It's not like 30 or 40k of either AS miles or AA miles will get you a first class trip around the world.

So unless there's a very specific redemption you're planning where AS would be a runaway winner I would probably stick with AA, since you can earn status and are east coast based. And of course AA's new Loyalty Points system is all spend based with lots of opportunities to earn additional LP's towards status with credit card spend, shopping portals, etc.