As an independent/non-affiliated researcher, what would I replace a logo with on a business card?
I have seen plenty of business cards, even for real businesses that do not use logos and graphics and just contain text. However, some are distinctive by the use of coloured card, and other features.

I have also seen personal cards that contain a photo in place of an icon or logo. Really useful to assist contact to remember who the card came from.

Its all about design and function really.