I think you're massively downplaying the other Dreams just to talk up the Harrenhall Dream, I mean for example:
Bringing Dorne into the Fold: If we do it by war, we could be talked up as another Conqueror that's possibly even better than Aegon since we did what he couldn't, which massively raises our claim to the throne, plus we are seen as an even better warrior and likely have most of the Reach and Stormlands love us.
If we do it through marriage, we now have a powerful King-Consort who will have no issues with our main bae Alicent, and we are still seen as having done what Aegon couldn't. plus if the Marchers revolt then we can annihilate House Peake and make the Manderlys love us even more and be our eternal allies.
Become an Exemplar of Knighthood: Our name is literally sung in song and legend and we achieve a reputation even more unapproachable than Arthur Dayne, meaning not only do people of our age love us, but people of the next ages will too, which also massively raises our claim to the throne since nothing our siblings do will ever make them be seen as great as us.
Master a Skill: We become a Law Giver even better than Jaehaerys, a singer better than Rhaegar, a tactican to make Sun Tzu green with envy, or able to make money appear as if from out of nowhere.
And then there's Harrenhall Dream: Yay, I'm approaching the point where I might finally start liking my siblings.
Given that the main appeal of the Harrenhall Dream seems to be our siblings will like us and won't be rival claimants, and that it fixes what people see as an unfortunate situation for siblings to have, doing any other dream would make our claim so good that any of our siblings or Daemon would have a hard time getting support, and it also might have the side effect that Rhaenyra feels so comfortable in her position that her unease goes away and she starts being nicer to her siblings.
Also I don't agree, I think of all the Dreams, confronting the vision with Aelora is the most likely for Rhaenyra to do without a Goal.