Well, it depends on the material and dimensions of the Leyden jar, of course. In the old days you'd say that they had "one jar" of capacitance. Wiki says for a "typical" one pint jar it is about 1 nF, but the voltage will depend on the thickness and material of the jar wall. For something like a polycarbonate beverage bottle it is probably around 5 kV or so. So a small parallel stack of the doorknobs I have would be superior in voltage and easy to make equivalent in capacity to a "typical" jar. The doorknobs have female-threaded terminals so it's easy to daisy-chain them with headless screws and to make connections to the ends.
"The easiest person to fool is yourself" -- Richard Feynman