This paper deals with a benchmark-based experimental comparison of three diagnose-based approaches for fault diagnosis of discrete event systems modeled by Petri nets: the MBRG/BRD approach, the FMG/FMSG approach and the SSD approach. The experiments are performed on a level crossing benchmark, using the respective software tools integrating the three approaches. Different features are shown in terms of state-space building (exhaustive or partial), procedure for analyzing diagnosability (based on complete or on-the-fly built states-pace) and state-space representation (concrete or symbolic). Based on the obtained experimental results, a comparative discussion is provided particularly regarding memory and time consumption for analyzing diagnosability of the three techniques