Something I've noticed is that a lot of people have a tendency of portraying Gregory as the “emotional one” and Manfred as the “logical one”, likely because Gregory is more inviting and Manfred is more cold. But if I'm being real, I think it's the other way around.
Manfred shows time and time again that he is an overemotional person. He lets his feelings get the better of him all the time. He literally screams because the turnabout goodbyes trial went over three minutes, and he kills Gregory and frames Miles for murder, purely because he was sour and wanted revenge. He may be smart and tend to plan things out, but he's also shown to be very prone to making sudden irrational decisions based off of his emotions.
Gregory, on the other hand, seems the more logical of the two. Sure, he's not as emotionally repressed as Manfred, but he doesn't have nearly as many outbursts, if any. He generally stays calm, and uses rational thought to guide his decisions rather than his feelings. Not to mention, him being the levelheaded, logical one fits narratively with how much Miles takes after his father. (Honestly I wouldn't doubt it if even the whole Logic Chess thing originated from Gregory.)
Ultimately though I think it's most interesting to make a kind of mix with them both. They're both emotional and logical in their own ways, and maybe they both lean more towards one than the other. But at the end of the day, they're not just flat one-dimensional footnotes. It's more interesting to make them varied, complex, and human.