Not sure who said it, but AS IMO would be the place to go if upgrades aren't important to you and you are sticking with UA as your main FF program. Not only go you get to redeem miles on a lot of varied carriers, but domestically speaking, you can get mileage for booking DL and AA (along with AS obviously). Might be the thing for you. And their mileage redemption is fairly decent and way better than DL.