The road noise is only partially due to the sound insulation. Part of it is the tires. The Mazda6 comes with relatively sticky Bridgestone Potenza tires that prioritize grip more than silence... well, that is, if you get the 17" optional wheels. I'm not sure about the 16", but I think the 2.3 only comes with 17's anyway.
It's not really bad, as almost any car with sports tires will sound louder than a car on "comfort" tires. Plus it's comforting to people like me ("old school") who like to be able to "read the road" through our hands and feet.
It's definitely more fun to drive. The Civic might be just as quick or quicker, but the drive is disconnected. The steering is light and somewhat numb, and the suspension can feel a bit floaty. The Mazda6, on the other hand, feels well-connected to the road, and is a joy to drive up to Baguio or Tagaytay.
Of course, like mbt says, since the Mazda6 is much more expensive, you've got to expect it to be good.
Other options at 1.4m? The Focus 2.0 Sport (1.1m) is also a nice car to drive. Quieter on the road than the 6, and it feels very solid compared to the Civic. Has a little more understeer than the 6, but that's curable with good tires. Para kang naka-Audi for half the price. Big news is a possible 2.0 turbodiesel version later this year. Kinukulit ko pa ang sales manager ko for specifics. Ang alam lang nila, it's coming in, but pricing and scheduling isn't definite.
The Mazda3, nice, but if you can afford the 6... hehehe...
I think the Sonata is finally priced out of your range. Sayang. It doesn't drive as nicely as the Mazda6, but boy, is it fast...

...you can ask at Hyundai, though... you might get lucky.
The Subaru Legacy might just be out of your range. It's probably not as quick as the Mazda6, being AWD and just a 2.0, but it's also kind of exclusive, and cool looking. Don't expect resale value to be much better, though.
If you're willing to look at non-cars, the RAV4 4x2 starts at 1.425. Decent drive (considering it's a Toyota), good looks, lots of space compared to other CUVs. Rumor has it that the new CRV will be a direct competitor, but no one knows the models and pricing, yet.
The Hyundai Santa Fe starts at 1.5m, drives well (for a midsize SUV/CUV) and has a terrific turbodiesel. Oh, and it looks niiiice.