The best way to visualize relationships between multiple datasets depends on the type of relationships you want to uncover, but in general:

• Network graphs work best for showing connections between entities (nodes and edges).
• Heatmaps are effective for identifying correlation patterns across datasets.
• Scatter plots (multi-series) help reveal relationships between numeric variables.
• Sankey diagrams are useful when tracking flow or dependencies across datasets.
• Knowledge graphs are ideal for complex, multi-layered relationships.

In practice, combining techniques (e.g., correlation heatmap + network graph) often gives the clearest understanding, especially when dealing with high-dimensional or interconnected datasets.