Well I think the east will win when the Bulls get things going. They're not too far from the playoffs now, so a couple of years of first round exits, another player or two, and another exit from a deeper round, and the Bulls may be ready

By that time chances are Eddy Curry will be the most dominant centre physically, and Chandler and Crawford are on the right path too. Rose might still be around. GO BULLS!
You never know the Cavs may get there if Lebron James is everything people think he is, and the Cavs build well around him. It'll take a good 5 years though.
You never know though, the Raptors were on their way, suffering some early playoff exits, and then getting deeper and deeper. They could have been that team had the progress continued, but things fell apart.
The rest of the teams in the east are probably as good as they're going to get, or maxed out financially, relying on the players they already have to develop. The Bulls aren't that far from the playoffs, yet their young guys have a considerable way to go in development. Other teams such as the Celtics or Pacers have players which are at or almost at their peak. Their go to guys aren't going to get much better, and the chances of signing good veteran (or non veteran) free agents are slim these days for eastern teams. It would take a massive shift of superstars from the west to east for any east team to win any time soon. Since that isn't going to happen, the most talented team has the best chance, and tha'ts the Bulls unless I'm forgetting someone?