Porcelain is low maintenance, good anti-slip rating, glazing keep colours forever.
Natural stone usually recommending by builders because the like to work with sandstone is much easier (don't need expensive tools, no need levelling system).
All boards in the bathroom recommended to tape joints and apply tanking. Alternative for hardie boards can be aquaboards moisture resistant boards.
The tiler witch do house 5 million pound with plasterboard I'm not impressed because the house is big and they have to save money. An expensive house doesn't mean they don't want to cut corners.