I would say that JD is a more interesting character than Del, at this point.
JD grew up in his dad, the living legend’s, shadow. He made mistakes, trying to measure up to his dad’s image. At the beginning of Gears 5 he tried to do right & save people, by putting himself in harm’s way, but even that went wrong. By the end, he was just trying his best to make things right & be better. He has stuff going on, basically.
Del doesn’t have much of a character, really. He’s good with tech & stayed loyal to Kait in 5. He has no obvious flaws though & it’s our flaws that make us human. I’d like to get to know him a bit better in the next game. Learn a bit more about him.
This is another reason why I think the choice works both ways. I feel like each of those guys would be deeply affected by losing the other. I think each of them can have a very good character arc in the next game, largely because of the other’s death. JD’s driven by guilt, Del’s driven more by sadness.