I think some of the highs in DR1 felt, well, higher than most of DR2's - but I'd place a lot of that on the inherent novelty and uncertainty that the first game had going for it. I think, sure, DR1's
setting evokes a certain oppressive tone and atmosphere to it that DR2's more open landscapes can't really capture, but I liked the inherent mystery of DR2's atmosphere and world more than I did Hope's Peak. There wasn't really any context to a lot of the abandoned rooms in the school, so it was a little hard to wrap your head around the desolation. I think the big emptiness of the island and how the game kinda parceled out more and more mysteries through its' locations as you advanced through the game worked much better. Seeing the ruins of Hope's Peak so early into the game was just a brilliant idea. Really helped kickstart your imagination.
I also preferred most of the characters in DR2 and I definitely preferred how cohesive they felt as a group. There was just a lot more time with them, a lot more time getting to know them, and there's a lot more time we get in terms of feeling out the group dynamic. DR2's characters in general just feel a lot more three-dimensional, and even if I hate on Kazuichi and Akane, even they have stronger and more developed character arcs and personalities than, say, Yasuhiro. It was a lot easier to get attached to people in DR2 (whereas I only really connected with a handful of characters, most of whom survived in the first game) and as such it hit a lot harder when they all started to, uh, die. The report cards in DR2 in general just feel a lot more meaningful and open about what they reflect about the characters. Like, as much as I love Asahina, I wouldn't really say her issues about her weight and how bad she is at dieting or being feminine have a lot on even her contemporary in this game, Akane (make no mistake, though, Asahina >>> Akane). I think, even the murderers in the game, Mikan aside (but she served as a fairly cool bit of foreshadowing) just had... much better reasons for doing what they did, and DR2 took exploring their rationalities over the act much more seriously, and sympathetically.
That all said, I do prefer DR's overall cast of surviving characters against DR2's. Akane and Kazuichi just weighs it down too much. Might have been more even if Chiaki didn't die, haha.
Story and dramatic tension was hands down much better in DR2 (bar a few situations where DR1 held a novelty advantage), though. DR2's so good at manipulating and controlling expectations (especially how it uses your assumptions from the first game) and so amazing at ratcheting up tension and keeping momentum going. It's honestly just a much more exhausting game to play than DR1, especially in long spurts. And as much as I love where DR1's story snowballed, the way that DR2's narrative escalated so extremely from that felt so cool and felt so right. I think DR2 was bogged down a little by reusing the Junko card (again, DR1 holds an advantage in novelty in this regard), but the thrust of the story beats and reveals really put it over the first game on the whole.
I'm also a big fan of the main theme playing right when you beat the last portion of the trial too. I'm a huge sucker for when games/shows do that. The ambient beginning of the theme is great too because it builds up into an awesome climax for the climax of the game.
You have no idea how much I adore the theme reprises in DR, it's just... argh, it's so good. Feels so cathartic and powerful when it finally comes in, and for some reason or another when the digitized 'DANGAN RONPA' title drop comes in... well, that's probably my favourite part of it all. Probably one of the main reasons why I feel DR finales are so great, haha.
Oh yeah, one of the best scenes next to this one (thinking of the Climactic Return song):
...was the one where Nagito wants to wrap things up quickly, so he tries to go over everything that happened in the case before Hajime can, combined with the appropriate music. Hajime's just like: "Wait... what?"
I think one of my favourite mindfuck moments with Nagito was the first one, where he interrupts you with Makoto's trademark 'you've got that wrong!'. I really did love that moment, though. It legitimately felt like you and Nagito were dueling for protagonist status the whole game.