which kind of job ranking and grading would you prefer and why? single grading system or job family grading system

Factor comparison allows for a more robust outcome, however the challenge is to rely on a specific standard against which comparisons can be made.
There are a number of Factor Comparison standards (Hay, Mercer etc.) that may be relied, however once a choice has been made it is necessary to mantain association with that specific standard as all subsequent activities (Comp & Ben etc.) shall be dependent on the outcomes and results.
Ranking method is useful for small enterprises with bench mark positions of less than 15 positions, work complexity is of a lesser degree and organizational positions are more so at a low to medium level of maturity.
The choice of selecting a particular method is more so dependent on the Organizational size, environmental/operational demands and available financial resources to be invested in such an activity rather than differentiating between different methods with varying degrees of complexity and maturities.