I hope Rey is related to Palpatine

That's what I hope for. It would be a great character arc for Rey, having been born from the dark side, but chooses to be good, all while occasionally being plagued and tormented by a savage inner darkness

It's by far the most interesting "related" possibility IMO, with some great drama potential. I just don't know if they'd take this sort of risk with Rey after they went out of their way to make her so lovable in TFA.

That's my theory as well. This would explain how she was so strong with the force in such a short time. She nearly defeated Kylo at the end of the movie. Why is she so strong with the force so quickly? If she isn't a Palpatine then I want her to be a Kenobi. Just please don't make her a Skywalker! That's too obvious.

I think its pretty clear she is the daughter of Han and Leia. Han feels bad when she talks about being left behind on a desert planet, Han knows who she is when Maz asks but the scene is cut, and Leia and her emotionally connect after Han's murder. Plus if you look back at the at famous picture of the first script reading, I think it's no coincidence that Daisy Ridley is sitting in-between Ford and Fisher. I think another clue is that Lucas wanted a movie about Skywalker teens and they just took off from that premise and had the two siblings go against each other (Ben and Rey) The poster also shows a parallel between them.

Palpatine or Kenobi: acceptable. Luke is not, too obvious.

most satisfying resolution

I am hoping for this too.

I certainly hope not. That would be utterly ridiculous!