The notion that someone who doesn't want power is thereby qualified is nonsense. It's true there are people who want power for fun and profit. But people who want to change things want power too. (The notion that motives can even be pure, much less that having mixed motives is a kind of evil in itself, is, sorry, childish at best.) Jon doesn't want to change anything. This is not a qualification for the throne. Cersei has it too! I can imagine Daenerys passing a law saying that no one can be compelled to marry their parents' choice. I can't imagine Jon even thinking of it. The only one apt to improve things has been shown to be Daenerys, which is exactly why the show hates her. Also, Jon is not a good choice because he is so easily manipulated, not least by Sansa. Somebody above thought the way he fell for Olly's treachery was a qualification for the throne?
The double standard for Daenerys and all other characters is extraordinary. The notion that Davos is a good man, when he has been pursuing claimants to the throne from the beginning is extraordinary. Gendry was one, kept in reserve, then taken up. Yeah, he's pissed about Shireen but he didn't have any problems with Stannis being a crazed fanatic who murdered his own brother. They notion that Tyrion is good when he murdered his own father with premeditation for the supposed crime of knowing (by supernatural means?) that even though Sansa disappeared he had nothing to do with Joffrey's murder, and Tywin would have forced him into a life at the Wall? Professor Zoom professes to believe that lex talionis isn't justice, but Tywin was basically murdered for being mean, not as a life for a life. Crookeddy would have been appalled, were any of it sincere. When Tyrion slighted Theon for feeling bad about a life as a hostage, it was the kettle calling the pot black.