Hi Dave.
I have not used the rubber type, the cork gasket seems to do the job well enough, but just ensure the mating surface of the sump pan, where the gasket sits, is flat and has not been distorted by having the bolts over tightened.
I think the main problem with the cork type, is that the securing bolts get put in too tightly causing not only the pan edge to distort, and it flattenes the gasket.