Hardwood flooring is nice and versatile but if a home is prone to drafts, it can tend to make it chilly when the months are cooler. Carpet makes a home more comfortable and cozy and the colors to choose from are innumerous but when it comes to matching with décor, determine if you wish for it to blend with the overall look or have the color stand out in boldness. You want to avoid a color that competes with furnishings so make sure it balances with furniture and its overall design.
Another important factor to consider (even with décor) is how much foot traffic the rooms see. Foot traffic almost certainly tends to influence the color that is chosen. For instance consider a light shade carpet that is exposed to heavy feet and shoe walking. Unless you want to shampoo the carpet frequently or use stain-repellant treatment, you want to avoid this so remember that light shade carpet will show up spots and dirt quicker than dark shades. Also remember that as more firmly the carpet fibers are twisted, the more scuffs and abrasions it will tolerate. If individual fibers are long, you will see less shedding, plus fibers will stay in one place, meaning in the carpet and losing carpet density will be greatly reduced over time.
So, if you are frustrated with floors that are hard and cold or dealing with 20 year old carpeting that no longer benefits from cleaning, consider new carpet. It may take additional care but there is no comparison to various types of tile or a floating floor and no substation as far as comfort.