Three things to consider before you choose.
Grammage describes the weight of a square metre of paper. Papers with the same grammage can feel quite different. Ask for a sample where possible.
Smooth, textured, coated or uncoated: the surface changes how colour and fine details appear. Match it to the intended use.
If a piece is made for writing or drawing, test your pen or pencil on the paper before committing to a larger quantity.