Oberyn should have won the duel for Tyrion
I’m not here to talk about arbitrary power scaling or anything like that. I believe, narratively speaking, that the plot of Game of Thrones would be improved with this change. Oberyns death is a bit of a turning point for the series; imo it marks the end of the golden era of game of thrones. With this small change, the show would completely avoid some of the weakest plot lines in the series. Tyrion in essos is admittedly interesting at first, but the novelty quickly fades as we realize that Tyrion is done having any impact on the story. He survives, but it’s still the death of his character. Jaime doesn’t go to dorne, marcella lives, and the sand snakes are removed from the story. So many poor writing decisions are automatically removed, and their replacements are much more intriguing.
Jaime would retire from the kingsguard and immediately go to casterly rock to rule. This would be so much more impactful for his character development, and we would finally get to see the rock. Tyrion would (probably) go to dorne with oberyn, just as they talk about in A Storm of Swords. This would open a whole new world of interesting plotlines, Marcella would be back in the story, and we get to see more of oberyn.
Outside of the changes, I believe the audience at this point needs to see a win. I understand that George wants to create an unpredictable story, but he already has. Ned has already been executed and the red wedding has already happened. George has created a story that radically subverts expectations to the point that the subversion is predictable. Oberyns duel would be so much more satisfying and surprising if it played out like a traditional fantasy story. Finally, after all the loss and hardship, one of the protagonists comes out on top with no strings attached. By being predictable, the story again becomes unpredictable.
Keep in mind, I have only read asoiaf up to this point. I can’t speak for the plotlines in feast or dance. I’m sure they are not as poor as in the show, but I still think my last point stands, even for the books.