I'm only a little ways in the RDR2, but I think it's safe to say the RDR1 had a stronger narrative focus.
So far, I think RDR2 trumps it in every other way though. One thing I think it really nailed overall, is giving the player real choice in how they want to play it. In RDR1, I always felt kind of guilty playing a bad guy, because it clashed so much with overall story they were trying to tell. Marsden felt like a hero with morals, so when you went on a rampage it didn't feel right. You wanted to help people more than hurt them in that game. With Morgan there is lot more shades of grey, and when you do spend all day robbing and killing folks and truly living like an outlaw, it doesn't clash with the overall morality of the character.
Not to mention just the sheer amount of shit you can do in RDR2 that actually feels impactful to the world, and less like simple side activities they just threw in there. The world Rockstar created in RDR2 is truly one of the greatest accomplishments in video game history. It's absolutely mind blowing.