Employee by employee, or by department
PlanGuru models labor costs at the employee level, which is slower to set up than aggregate planning and far more accurate when start dates, salaries, and tax treatment vary across your team. Prophix One works bottom-up and shows employee costs by role, department, or project. Visier and Workday Adaptive Planning lean toward connecting a workforce plan to a financial plan rather than costing every individual line.
The honest question is not which is more precise. It is how much precision your planning cycle can maintain. A per-employee model that nobody refreshes after the first quarter is worse than a departmental model that stays current.