Given the scenario that Chad layed out, I would take Walker in the Spurs place. That would leave them with
Bigs - Bonner, Duncan, Oberto, Mahinmi, Splitter, FA (Likely Thomas resigned with Bird Rights)
Wings - Ginobili, Barry, Bowen, Udoka, Walker, MLE FA
PGs - Parker, Vaughn (He has a player option for another year, which I suspect he will take), 2nd round pick or FA for the LLE
Picking Batum to leave him in Europe puts them into a weaker position, as they will be forced to either go for a player for the minimum or split the MLE. If they intend to offer a short contract (in accordance with the Major rebuild in 2010 scenario), splitting the MLE would leave them very short of leverage...