Spiral staircases are a good option for small houses, as they significantly save space.
The material for the manufacture of such structures can be either metal or natural wood.
The basis is a special pillar or rack; the steps are attached to it.
The question is what budget have you allocated to purchase the march. If we talk about design projects, metal will cost more than wood.
For ready-made serial products you will pay 2-3 times less (depending on the complexity of the shape, type of material, finishing and amount of decor).
Concrete stairs are stronger and more durable due to the absence of installation joints.
A wooden staircase creates additional load on the walls; over time, the structure becomes loose and requires regular inspection and repair.
From a fire safety point of view, a concrete staircase is preferable.
It is better to make the stairs light.
This solution is in harmony with any color scheme.
It is permissible to use no more than 3 contrasting colors in the decoration of the march (in black-white-beige, beige-brown or green-blue).