I just finished up my first playthrough of RDR2 and Blood Feuds, Ancient and Modern is my favorite cinematic like mission I've ever played in a video game. The atmosphere, the music, that moment at the beginning when you realize the whole gang is going out was just something special.
That's a great one. Since I only beat the story once, I'm having difficulty remembering if they were actually cutscenes or just highly stylized in-game moments, but whenever they used actual songs they wrote for the game, it resonated with me. "Unshaken" playing I think after Guarma, that gave me goosebumps. "Cruel World" when the epilogue starts and John and his family are riding through the country - the simplicity of that really got me. And Arthur's last ride, with "That's The Way It Is" playing and quotes from various characters throughout the story actually made me shed a few tears. I think that might be my single favorite moment in the game, it's an extraordinarily moving scene and I can't wait to get to that point again.
I think if I had to pick out a weak spot in the game, one thing that comes to mind is Guarma. It's not bad, but I remember thinking it just wasn't that necessary in the long run, that it was too different. I wonder if I'll feel the same way this time. I was perfectly happy staying in the old west, and was kind of annoyed there are animals there that you can't see anywhere else, if I remember correctly, so I was never going to see them again. I don't like missable content especially in games of this size so I've also been carefully paying attention to what I might be missing before I move on to major story beats.