Knowing the Mirage (especially the manual) had a somewhat dependable powertrain was important to me. I will even add Fummins' experience with these cars helped convince me that these economy cars were ok, even though he doesn't own one personally.
I think the Prius C is a well built car. It's known to be super reliable (maybe the most reliable). The Prius C is reliable & economical, but it's highway mpg rating is exactly the same as the Mirage. I bought a Mirage, because I could buy a brand new one for under $10,000. Paying a lot more for Prius C wouldn't make me enjoy it more. The Mirage with its simpler technology does everything I want a small economy car to do. It also has a charm of its own.
If I paid a lot of money for a new Honda CRV that has 1.5L GDI engine issues, I would not be a happy camper. If the solution is changing your oil more frequently because of the gas in your engine oil, I am not impressed by that. If I bought a new Honda CRV today, I would buy the base model. Not because I am cheap, but because it has their proven 2.4L engine in it.
The desire to crank large amounts of horsepower out of smaller engines comes at a cost. I am not saying everything out there is junk, but there is a lot of unproven stuff being thrown at consumers. I am not impressed by that. Buying a new vehicle shouldn't feel like going to a casino with your money.