Part of the "analysis" is that criticism of Trump has no effect. He in fact revels in it. Hillary, unlike Trump cares, (or knows she must appear to care) enough to refute the negatives/attacks.
Something that should sound like nonsense, yet is somehow relevant this election cycle.
This is my thought as well. Trump not only has massive amounts of material on Hillary already, but can make use of any attack she levies against him to his advantage. I don't think she's smart enough to remain in her own corner and refuse to throw punches. On the contrary; I think Hillary is so egocentric that she won't be able to stop herself lobbing shots at Trump only to find them deflected back at her with interest. Even though by now she must know for certain that negative campaigning against him will only help him and that trying to win an insult war with him is futile, she will do it anyhow. The victory between them would come down to who can smear the other better, which more specifically means how well Hillary adapts to his approach. If she botches it she'll lose, and a headstrong approach could very well botch it.
Sanders, on the other hand, has nothing substantial in his personal life to pick apart, and in fact his public life has been decent enough that even approaching that topic would only help him. Trump could, of course, go after him for not being a political power player, but that's a wash since neither is Trump. It's a card that Hillary could pull against Sanders, but Trump cannot. We also know that Sanders refuses to campaign negatively, and even when he feels another candidate has done something wrong he is very hesitant to publicly criticize them for it (see: DNC software malfunction). In effect, Sanders would give Trump no ammunition to shoot back, and would never fall for being manipulated into rebutting insults Trump throws at him. This leaves the content of the potential race between them being between the actual issues, and that is exactly where Trump would go after him. Trump would go after the word SOCIALIST from square one and would never let up on that subject no matter what Sanders replies. Trump might go after his age or something, but most attacks by Trump would be against Bernie's actual proposals - which is a good thing! It would mean that the election would boil down to what the voters think about the issues. I would call that a good result, either way.
If it's Trump-Clinton it will come down to who's better at media wars, and frankly I don't like her chances there. She cannot effectively out-demagogue him, so I'm not sure her chances are so great as some people think they would be. Even if the conspiracy theory is true that Trump was a Clinton plant that would surely cease to be relevant should Trump win the candidacy. All bets would be off and he'd he out to destroy her.
If it's Trump-Sanders I feel it would come down to the debate on the issues, and incidentally I think the debates would be a lot more interesting between these two than between Trump and Hillary. In any case they would be a lot more respectable. Another point I'll make about this match-up is that both Trump and Sanders have branded themselves as outsiders who are against business as usual in Wall Street in politics, super-pacs, and lobbying. They both don't take pac donations, both want to revisit the idea of trade deals that export American jobs (they are both against TPP), and both want to help the middle class. In fact these two have more in common that it would at first appear, and should they go up against each other the areas where they agree (of which I think there are many) would be a total wash and they'd each have to focus on the other areas in order to differentiate themselves from each other. And here's were it gets interesting, since the areas where they disagree are in military policy (Trump wants to increase military spending, Sanders not), immigration policy (obviously), and all of the 'socialist' issues Bernie believes in. Meaning - they'll be forced to discuss the issues that are actually most contentious.