It depends at lot on how you use them, and where you do and don't have status, and perhaps on how tall you are. If you have AA lifetime plat Status (like I do) but no AS status, AA status works on Alaska flights if you book with AA miles (or book paid using AA FFP #), but not if you book with AS miles (there's then no link to your AA status). So I get access to better seats on AS if I book using AA than I book using AS. (I'm fairly tall, so exit row or extra-legroom seating of another kind is fairly important to me.)

And DL int'l redemptions up front (again, for the legroom) are hard to come by, so the fact that AS also partners with DL doesn't excite me. (I already have a bunch of DL miles and they never work when I need to go to a location that SkyTeam flies to. Are AS miles really going to work better on DL than DL miles?)