For planets that are solid objects (like the Earth) a single rotation period can be given unambiguously. But for a gas giant such as Jupiter or Neptune there may be more than one value, depending on where the rotation period is measured. For such planets the standard is the internal rotation period, although alternative measures of the gas giants' rotation speeds would not affect the comparative performance of the different planets. For the four planets in the question we have, to the nearest minute:

Jupiter 9hr 55min

Neptune 16hr 7min

Mars 24hr 37min

Mercury 58 days 15hr 30min

So, although Jupiter is colossal, compared to the Earth, it spins on its axis more than twice as fast as the Earth!

More Info: en.wikipedia.org