Agreed. I would say UA has the slight edge over AA when comparing legacies, but the growth of WN at MDW in the last 10 years can't be ignored. I know more than a few people who have shifted their allegiances in the last few years from AA to WN so that they could use a companion pass.

In general, I agree with the sentiment that destination matters -- if you're headed to the east coast, AA has a slightly better network, whereas UA does a little better to points west. UA has a much stronger international presence, especially to Europe, whereas AA has removed flights like FRA and DEL in recent years in favor of relying on alliance partners and codeshares.