I've never heard of the Honda C, but I prefer it? Why? Because the average Prius owner is a rich, self-righteous liberal douche who likes to think they're saving the environment, while really doing the opposite. They get pretty mediocre mileage for being so "technologically advanced" too.
But over either of these 2
PR tools, I prefer a diesel, any diesel. Diesels are the most environmentally friendly out there (not counting non-production specialty cars) because they run on vegetable oil. Anyone filling their diesel with petroleum is doing it wrong.