It's a good question, but I don't think anybody knows the answer to this.
More playing time is supposed to help development. So is better coaching.
If we assume your AAA coaches are better than your AA coaches, is it better to have a prospect in AAA for 1/4 of season and no playoffs or AA for the entire season and 1 or 2 rounds of playoffs?
For better or worse, WIS doesn't give this level of input on how the game works. And you'd have to run hundreds of tests before you'd likely get a significant result.
If I had to pick an answer, I'd answer it doesn't really matter. At most, it would be a 1 point difference in about 1/2 the categories. Not going to matter much in how the player performs.