The Optima looks nice, but its a piece of junk. There's always something wrong with them, and they loosen up and get old fast. I'm a factory authorized tech for a several brands. Here's some general comments based on what I've seen working on them.
Hyundai/Kia - As you go up the line, the worse the car gets. They're just trying to do way too much all at once. Each time a new version of a car comes out, there's usually massive upgrades that are not fully tested. The Elantra/Forte is actually a much better car than the Optima/Sonata.
Mazda - The new 6 is probably the best car Mazda ever made. There were a few small recalls when it first came out, but overall, the car is built like a tank. Its not a race car, but the trade off is 185 horsepower motor that gets 38 mpg on the highway. There's hybrids that don't get that kind of mileage.
Infiniti - Practically indestructible. For some reason, the G37/Q40 sell for very reasonable prices on the used market. If you want a fast mid size sedan, this is the one to get. Needless to say, you won't get the best gas milage. Also, and this is important, Infiniti doesn't use CVT transmissions like Nissan does. I wouldn't buy a CVT regardless of brand. They drive like crap and they don't hold up.
Ford - Walk. You don't need a car that bad.
