I think I'd take Wiggins over Parker, simply because I think the NBA game will agree with Wiggins and that he'll develop into a much better scorer over time than we've yet seen. I also like his defensive potential, compared to Parker, who might end up, like Melo, being best hidden at the 4 spot next to a large center. I'd be thrilled to end up with either, though.
Randle is a tough case for me. He's probably going to be a similar player to Zach Randolph or David Lee, but I'd worry that he might end up closer to Carl Landry or Ty Hansbrough. I feel like he might be the most NBA-ready player in that top 5-7 group, but his role is going to be essentially the same as the one Sullinger has played for our team. The two couldn't possibly play together.
Danny could always trade whichever of them he thinks has a lower ceiling in exchange for a player we can use now, but I don't like the idea of being somewhat forced to make a trade like that. If you're trading a young player on a rookie contract with a record or expectation of high productivity, you want to get the best return possible because that's a really valuable asset. Having the appearance of "needing" to make a trade doesn't put you in a good position to do that.