Resource Leveling and "Optimization"

Im trying to familiarlize myself with how resource leveling works in the various scheduling packages and wanted to find out what the members here think about these features. I know how Microsoft Project does it but would like to find out how it is done in Primavera, Workbench, OpenPlan and Planview.

Everybody says that the way that Project does it is ’the worst’ but nobody ever says why the others are better.

Thanks in advance.