I haven't tried trading James, but below are my suggestions. I'm assuming you aren't worried about realism (especially since James wouldn't ever be traded by the Cavs)...
If your purely looking for picks:
Trade with the Celtics (they have tons of 1st rounders), and are looking for a centerpiece to build their franchise around. Problem with Celtics is they don't have anyone you are looking for (Athletic Wing/Star Big)
76ers also have quite a few picks, not to mention Embiid and Noel which would be great bigs to add to your team. Love/Noel or Love/Embiid could be a pretty nasty combo. Have decent role players win Wroten & McDaniels is you want an athletic combo guard. as well.
If you looking to get replacement player & a pick or two:
Jimmy Butler definitely makes sense. I believe this is a contract year, and trade him for Lebron plus a couple picks (Chicago has picks to give). They also have some great role players in McDermott and Mirotic you could add with Butler.
Call me crazy but what about Batum for the Blazers? Not quite a superstar, but he is a great shooter/defender/all around player. He may not have the potential of Butler, but I've absolutely loved playing with him. Problem is, I don't know who else you could add to that trade.
Or call the T'Wolves back and tell them your sending James north for Wiggins and picks/a couple other players... You get a high potential youngster with a couple picks/role players and give the T'Wolves an immediate playoff hope.
Again just my input, no worries if you don't like any of those...
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