Both are fine. It should be in the same family as the rest of the space. Granite tends to be more harder, weathers slowly. Light colour granites absorb water and change colour, darker granite is more dense. Marble is definitely porous, absorbs water and softer. As per site condition and usage, application is advised.

Thanks, Instead of Marble or Granite any other thing we can use for the STAIRCASE?

Composite quartz , composite marble from Kalinga, Asian and other brands can also be used. If budget permits, real wood can also be used. Glass, Metal chequered plate, steel and special tiles in single piece from Nitco and other brands can be used for staircase. And once again, everything is subject to site condition and utility.

Agree with JSH Architects.

Alternate materials you can use are larger tiles that can be cut to cover the entire tread of the stair, concrete finish, and solid wood (which may be slightly high on maintenance but looks beautiful. Also expensive). The answer lies in your interior palette and design.

You can use pretty much anything if your handrail material is black-painted mild steel. If it is chrome (SS) and glass, then stone or tiles are better options.