What industry do you think your business is most related to?
What do you have in mind for the style and theme of the stationery?
Before I had a Matte black card because my logo was white and I had black on black on the back. The card thickness was greater than most cards and the top left corner was curved. It was more of an artistic design.
I think something professional and sleek, yet unique would also be cool. I think since the logo is grey maybe a white or off white card would be cool?