In the current environment, I wouldn't be worrying about the next up and coming commodity, stick to Gold imo. I suppose if I HAD to go for a particular industrial commodity I would go for one that is used in some way in agriculture (food shortages are an increasing problem). So potash, vermiculite etc.
Several goldies in that list are quality, though some imo are probably worth discarding (am not going to point out which ones because no doubt I would start a heated argument)...again I would stick to the ones that are focussed on high grade gold (either exploring for, or producing), and as Nathan pointed out, make sure they have good management (check their track record). That for starters will be a good way to weed out the undesireables.
Would probably also stick to those that are operating in a country with little political/social risk - whilst they may have great projects and great management, will count for nothing if something blows up (eg a political coup etc).
