The construction of a yanagiba is designed to have cut surfaces that are clean and smooth that maximizes and maintains flavor. The presence of the concave grind (urasuki) reduces drag when slicing. The urasuki also ensures that your edges are in contact with the stone during sharpening.
Sujihiki, on the other hand, is a more versatile slicer. Its double-bevel and slight flexibility give it a more robust edge compared to a yanagiba. If you are not a sushi chef, a sujihiki is the better option. The sujihiki is a perfect for raw and cooked boneless protein (roasts, ham, etc.)