The graph in MacHG is much prettier than sourcetree's.
It is curvy - lines are easier to follow.
Colors are higher contrast - lines are easier to follow.
Commit nodes are the same color as the line, except for merges - makes it easier to pick out commits that are interesting in the tree.
The tree is not always 'compact' - branches change direction (column) much less frequently, so they are easier to follow.
