I think the D League is better than most of D1. If he's in Kentucky beating up on Ole Miss I don't think that helps him as much as a D League game. But if you're on Duke or UNC in the ACC or maybe a top team in the Big Ten or Pac 12, I think that's a better place to be developmentally, at least if your coach is good.
I definitely think the level of competition in maybe the Elite Eight is on par with typical D League and the competition in the Final Four is better.