DeMar DeRozan’s advantages:
Better ball-handler/playmaker:
Buddy Hield is the better shot creator for himself but DeMar DeRozan is the better ball-handler and creator for his team. If DeRozan was three inches shorter he would have probably been a point guard and would have been a fine one at that.
The best type of player to put alongside LeBron James is a ball-handling guard that knows when to step aside and be an off-ball threat. DeRozan is just that and he is similar to Kyrie Irving and Dwyane Wade in that sense (obviously not being as good as those two).
Defense
The Los Angeles Lakers really value defense and DeRozan is the much better defender. DeRozan is not a great defender by any means but he is serviceable and in the right system can definitely hold his own with who he is guarding.
That is not the same case for Hield, who is a well below-average defensive player. While you can mask Hield defensively if you have an elite defensive guard like Alex Caruso also on the court, he does still present a matchup problem when you play teams with elite backcourts, such as the Golden State Warriors.