Since this is my first year as AA Executive Platinum(one world Emerald), I thought the one world alliance benefit is similar to Star alliance, but it turns out to be a lot better. When I tried to enter Admiral club at ORD when connecting from Shanghai, the agent told me I can also use Flagship lounge around K19, I was surprised when I heard that.
Later I went to oneworld website and learned that as one world Emerald, I have access to all First Class and Business Class/Frequent Flyer lounges in addition to use First Class Check in counter. Those are the benefits you don't get as Staralliance Gold.
Still, both alliances are great and make Skyteam the weakest alliance.