I have often pondered over this question too but never have I been able to come down to one factor. But it makes a very good topic for discussion :)
Here's my take:-
You see, I think, we start off by answering 'What is Journalism?' then there are so many beats in what make up news. Also today with the cropping up of infotainment/advertorials the line between journalism and PR has thinned down.
I also remember having attended a discussion where my professor posed the question - 'Can Wikileaks be categorized under journalism?' So then, can we award Julian Assange for breakthrough in journalism because he lifted the curtains and provided classified information to the hoi polloi which helped them change their perspective about their Government or the functioning of this world?
Now when we talk about the quality of the news, how do we measure that? Is it a newspaper informing me daily of the reforms in the political environment? Or the developments in science, arts and economy?
When we talk about risks, I am particularly reminded of CNN's Christiane Amanpour for her Gulf War coverage and Al Jazeera's Ayman Mohyeldin for the Gaza war. Taking risks by being on the war front and providing the rest of the world with information is a commendable job.
Media Activism/ Trial by Media is also another sub-topic which can't be ignored. Many a times in democratic countries, Media has taken the role of judiciary by involving investigative journalism and pressuring the court via public support to deliver justice ( because the media thought it had been denied).
What qualifies as breakthrough journalism is a good question but I guess until Journalism too becomes a licensed profession with its own code of ethics, it would be a little difficult to define the parameters for judging excellence in journalism.
