Rhaegar's victory would probably be better for the realm, as I believe he'd be a more capable king than Robert and he'd keep Littlefinger and Varys and maybe even Tywin away from (too much) power. So if I lived in Westeros, I'd want Rhaegar to win. But the story we'd have wouldn't be as exciting as it is now. There probably wouldn't be a a war of the 5 kings, Jon wouldn't go to the Wall, Dany wouldn't be an important character and there wouldn't be any dragons. So as a reader I like it the way it is. What about you?