At Carpet Class we have always promoted Wool carpets.
Wool is naturally cleanable and anti-static, keeps it shape well and bounces back in areas of foot traffic.
Wool is often mixed with man-made fibres in a 80:20 ratio to produce the yarn used in cut-pile carpets such as twist-piles, velvets, Axminsters and Wiltons.
The weight of the pile (usually measured in ounces per square yard) and the density of the tufts (the gauge) is a good indication of how hard-wearing a carpet will be.
These "upright tuft" carpets are extremely cleanable both on a day-to-day basis and also with professional "steam" or "hot-water extraction" cleaning. (Click on the "A-Mark" link opposite.)
100% Wool yarns are also used to make loop-pile carpets.
Although very popular because of their "natural-look", loop-pile carpets are not quite as durable or as easy to clean as the cut-pile materials.
Look for 2 or 3 ply yarns rather than single ply yarns for improved durability.