It's a moving target with a ton of variables, and even when you do finally figure it out they could make some boneheaded change (like 50% EQMs) that upsets the whole balance.

Truth to tell, many FTers are hub-captive biz travelers, so it's very hard not to go with the airline that has most of the non-stop flights in a business situation. In ATL, for example, DL is still dominant, even though you can bang your head against the wall trying to use DL miles for an award trip to Australia.

Whatever you do, don't hoard too many miles. They won't earn interest or appreciate in value. I think when the baby boomers retire you'll see a lot of people wanting to tap into huge balances accumulated while working, and that'll put more strain on already strained availability.