Above: Leblanc "paperclip" extended Bb contrabass clarinet (range to low written C, sounding Bb), and an Orsi Eb contrabass sax. Note the difference in the cylindrical bore of the clarinet, as opposed to the expanding conical bore of the saxophone. An instrument with a cylindrical bore sounds lower in proportion to its length than a conical one, so the sax has to be larger to go as low as the clarinet.
It seems hard to believe from looking at it, but this particular contra clarinet actually can go a third lower than the sax (Concert Bb vs. concert Db), thanks to several extra keys. It also has more finesse in soft passages. But the sax wins hands down for presence, power of sound, and seismic potential!
