I always thought DR2's cast was a strict upgrade in almost all respects from DR1. From an individual standpoint (to the extent I had so many favourite characters and literally all of them but Sonia died :negative
and from a group standpoint. Because really, there wasn't much a 'group dynamic' in DR1 at all. Characters stuck to cliques and the morning breakfast was a formality that was half the time ignored by a number of people for any number of reasons. Some characters felt totally out-of-place in every situation, too, like Yasuhiro. The only time that the 'group' actually galvanizes is around the time that Sakura's real letter is revealed, and not many people were actually left by that point.
Admittedly, there's perfectly good reasons for it - DR1 sets a very different, outright uncooperative tone within the group. People openly distrust other people and they form cliques because they feel safer dealing with them than the whole, but it didn't make for anything particularly 'cohesive'. I can totally understand preferring this, but I can't really agree that DR1's characters 'meshed' better than the characters in DR2 by virtue of not meshing at all. DR2 was a lot more invested in showing how everyone got along in the group. There's a lot more 'group activity' events where everyone's having fun or playing off each other, and a far more forward and cooperative tone amongst them, plus the optional events that often grouped characters that otherwise never got to interact with each other much together for a nice little event.
I found myself much more keen on DR2's approach, really.
I think it's a little clever, too. The world's last hope were bottled up in Hope's Peak by Monokuma and they immediately drew lines and distrusted each other. The Ultimate Despairs get put in the same situation and they more or less established a general atmosphere of trust fairly quickly.