**Generally for a 4-connected grid graph the Manhattan option should be used as it is the true distance on a 4-connected grid. For an 8-connected grid graph the Diagonal Manhattan option is the mathematically most correct option, however the Euclidean option is often preferred, especially if you are simplifying the path afterwards using modifiers.**

**For any graph that is not grid based the Euclidean option is the best one to use.**

Manhattan => 4-connected grid graph

Diagonal Manhattan => 8-connected grid graph

Euclidean => not grid-based graph

For the hexagonal grid graph, which is the 6-connected grid graph, which Heuristic should I use for it?