No contest, Hillary won this debate. I'd say the margin was 70-30. Most of Hillary's statements were policy driven, reinforcing the fact that she basically knows what she's talking about and -- for all intents and purposes -- can be trusted to not run the country into the ground. She took up most of the talking time, but it wasn't just about attacking Trump. She made the argument for why SHE would be the best person on the job, though intellect and temperament, policy and substance.
Most of the topics set up key opportunities to attack Trump though....especially the fitness question. It was a no-brainer who would give the best answer, and Hillary did just that: she gave the best answer: all you had to do was go over the last few days/weeks/months in which Trump became a national embarrassment. And she prosecuted him, not in a mocking tone, but in a tone of warning and caution, which is a lot more persuasive. The rigging portion really nailed him.
In a word, she was Presidential. Trump was a lot more restrained and disciplined this time, but I'd say that this debate was a lot more on substance than mudslinging, and that never benefits Trump.
EDIT: If I were to grade them:
Clinton: A-. She communicated directly to the people about her plans and goals, and did a tremendous job making the case against her opponent.
Trump: C-. He was less unhinged, but clearly didn't come prepared for certain topics, as shown by his transparent pivots to completely unrelated topics. Hillary did it, too...but she at least TRIED to tie two unrelated topics together. Her pivot was a transition; his was just a messy rush to spit out an answer.
Wallace: B+. I felt that he was a little tougher on Clinton, but he managed to inject some levity into the debate to diffuse some of the more tense moments. I thought that was a good tactic.