I prefer platinum to steel because of its hardness. Platinum is very dense and therefore a very durable case material. It is difficult to work so many platinum watches have white gold parts (usually the crown). It is ideal for sports watches because it would be very difficult to scratch. It is heavier than steel if that is a preference. A rare problem, but one experienced by some forum folk is an allergy to steel (no kidding--supposedly 10-15% of the population). Platinum does not tarnish the way gold does. Obviously one of platinum's major disadvantages is cost.

I don't see the advantage in having white gold over stainless steel except in terms of aesthetics. There are various alloys of white gold so even that is not a given. Some white gold have more gray, some have more blue, some have more yellow and this depends on what the watchmaker wants to achieve. Gold is softer than stainless steel so it scratches more easily (and is also easier to polish). It is heavier than steel, but lighter than platinum. The "better" quality white golds are used by Lange and Blancpain. But gold tarnishes and white gold is not as easy to maintain as yellow gold. I would not get a white gold watch if I could help it.

Tantalum is another material that is finding its way into watches. Audemars Piguet has made a mostly tantalum watch (mixed with platinum parts). It is almost as dense and durable as platinum and almost as difficult to work. But it is more readily available (mostly from Canada) than platinum and has a warm silver gray finish. It is less expensive than platinum and offers almost the same benefits.

You didn't ask about titanium, but it too has advantages over stainless steel. It is non-corrosive so it is ideal for sports watches and dive watches. It is less dense than steel and is subject to similar dings, but it is also a lot lighter. Some have criticized the light weight of a titanium watch because it is too similar to the heft of a quartz.

I am still waiting for a watchmaker to us allurium.

Someone who gave me great advice on white gold is a Watchnet banner dealer, Albert at European Watch (I think he has three engineering degrees). I have a feeling he knows a lot about all watch metals.

Best wishes.

Robin