I just sold my Mazda 3 to get an SUV as we needed the space. But, I LOVED that car. It was a 2006 model, so I can't speak for the new ones, but I got great gas mileage. Also, I'm short (5'2"), and visibility was very important when I was looking. It had the best visibility and handled the best as well. My husband has a 2007 Mazda 6 and loves it as well. It is larger though, and has more of a sedan feel. Great car though.
My mom just got a new Kia Optima and loves it, it gets really good mileage but I don't know too much about it.