Dany's choice for husband is obvious.
Look, Dany herself told Dario she has to marry. Unless she makes SJW's everywhoere moist and marries yara, there is only one true choice.
She can't/wont marry Tyrion, even if he were recognized as Heir to Casterly Rock, and Jaime is sworn to the Kingsguard. Plus, Dany would have him killed for murdering her father. There are no other Lannister males.
There are no Tyrell men left...Mace and Loras and lovely Margery are all dead, ruling out a lesbian marriage (sorry SJW's).
Tommen is deceased as well, poor weak male.
There are no males in Dorne. Plenty of girls though. Perhaps dany will marry one of them, preferably Obara. But, lets assume she is going to marry a male for a moment.
There are only 2 remaining men of power in Westeros; Euron and Jon Snow.
She obviously won't be marrying Euron. She already has a Greyjoy fleet, and she'll pull off his balls to show that Feminism > men. She won't marry Theon because he is submissive to Yara, and would be seen as weak/pathetic and a turncoat besides his balls are already gone, which is the way Dany likes her males. Submissive or neutered, and Theon is both.
Jon is an illegitimate bastard King of the North and her nephew. He's also died, so he likely cannot sire a child on her, plus it's implied she is barren anyway. Jon COULD be the husband, but there is one more obvious choice....
STANNIS THE MANNIS.
Their marriage would unite both previous regiemes....Targaryen and Baratehon. Stannis is already of her religion (Red God), and rules at Dragonstone. It makes sense. Plus, she would submit to his unbreakable masculinity, and he's the only man alive that can sire a son on her.
Say, do you hear that? It's the sound of the Reaper.....