The Prince that was Promised: There are so many fan theories and changing information that I don't know what to believe. All I know is that the entire show seems to revolve around Jon Snow and his story. Danereys might seem to be separate but now we see that she is also woven into Jon Snow's story-line and not the other way around. With so many arrows pointed at Jon Snow, I have to believe he is going to be the Prince who was promised at the very end.
It's plausible that Jon actually kills Dany because in the Azor Ahai prophecy he has to murder his wife in order to forge Lightbringer and end the Long Night, however with what the show has become now it probably won't happen because of all the Dany fangirls that would probably cry endlessly if this happened