assuming you dont care about getting the 100% mileage bonus using your AA platinum status you are better off using MP as an MVP on AS. Whatever small chance there is to be upgraded as an MVP, your chances as an AA platinum would be 0. AFAIK using AA elite status on AS gets you preferred seating and priority boarding and maybe a free bag. No upgrade benefits and I was going to say no change waivers but nevermind AS still gouges MVPs at full change rates even though they should make it $50 or $75 for them