I don't have experience with DL 360 or AA CK, but as an AA EXP they have happily opened up domestic saver F to connect to international saver J for my whole family, something United would only laugh at doing.

AA SWUs also have no fare class restrictions and there's more confirmable space as an EXP than there is for UA GS. Doesn't hurt that AA still publishes an award chart either.

AA also allows for elite benefits on basic fares, such as E+ seating, comp upgrades, confirmed standby, and SWU usage.