I have much experience of HydroWorks and SWMM, and some of MOUSE. HydroWorks and MOUSE are more or less similar. They are just two concurrent software of this sort. They are much user-friendly than SWMM. As to the numerical engine, I don't know which one is the best. However, I have never been disappointed with HydroWorks!

ir. Mingchuan Ruan
M.Ruan@ct.tudelft.nl