Melenchon, he's the only one to really care about ecology in an efficient way, students and women. Austerity is not the solution here and he understood it well. Too bad he has a bad reputation because the media don't like him, a bit like Bernie Sanders : almost the same ideas but "too old, not that handsome and a bit grumpy.
I do not see how Hamon could change anything as he is stuck with the PS (Hollande's government), how would he get rid of El Khomri law if she is still in the government, same think for Valls etc.
As for the other candidates ... hahaha !