metal golems

If money is no object and you want the most powerful golem warrior available, you want a metal golem.
There is no reason a modern robot cannot be made out of many types of metal, but due to metaphysics and SCIENCE!, a metal golem needs to be at least 95% composed of a single type of metal. The vast majority of metal golems are iron golems.
Iron golems are perfectly capable of sweeping floors and passing the butter, but they are extremely expensive, so they are nearly always put to martial use. They are commonly used as body guards for the wealthy and powerful, especially mages.
Iron golems have two sub types: steel and cold iron. Steel golems are a lot more resilient to damage than cold iron, but cold iron golems are slightly resistant to magic and they are terrifyingly effective against Fair Folk and spirits. In case it needs to be said, a spirit cannot be bound to a cold iron golem. Steel golems are cheaper so they are the default variant used unless the golem crafter is seeking a specific anti-spirit or anti-Fae weapon.
Iron golems have two common design types. Iron golems can either be made of solid metal or they can be hollow. Hollow iron golems looks exactly like a decorative suit of armor when it’s not moving whereas a solid iron golem is always obviously a golem, even when inert. Hollow iron golems are slightly faster than solid iron golems and are much cheaper to build. Solid iron golems are much more resilient to damage.
Bronze is not as strong as iron, but if it’s polished it can shine like gold. Golem users who value aesthetics over functionality sometimes favor bronze golems. They only slightly cheaper than iron golems, but they are much weaker in combat, so they are mainly a vanity golem for the very rich.
Silver golems are naturally extremely expensive, but they are capable of doing far more than looking pretty. Silver golems are extremely effective opponents against undead, lycanthropes and demons. They are however, more vulnerable to conventional attacks than iron golems. Besides the raw cost silver required, silver golems require at least a little bit of sovereign silver be incorporated into their construction for the magical enchantments to stick.
Metal golems are usually alchemically treated to be immune to rust and never need sharpening of any blades or points. If they are not, a golem can be made cheaper, but it will not last very long. Most golem crafters build their golems to last.
For the RPG mechanics of creating clay golems, check out Metal Golems by the Numbers.