most durable and easy to clean fabric?

We have a wood stove running all our central heating and hot water in the lounge, so even tho we're careful we get a lot of ash dust flying around and bits of bark sticking to our feet, so our sofa gets grubby quite quickly. Loose washable covers would probably be wiser, but, for comparison, please could you tell me which of your fabrics would be the easiest to clean (rub with soft cloth and upholstery cleaner spray, I guess)? I guess anything with a mixture of synthetic fibres in?