Both have their place in Bass Guitar history, and rightly so.
Nothing more to be said on Jaco - All been said, and in depth.
They both had a great input into Bass playing, and both very serious musicians.
But they both put out some rubbish playing wise.
I am a real Jaco fan, but towards the end, his playing wasn't on top of it.
Same for Jack as well, on some of the YouTube clips his intonation and solos
were not up to what you would expect from him.
But then again, did I read that he had developed some hearing problem?
Jack was also a trained Cellist as well as an upright player,
and had decent Piano chops as well, along with a back ground in Jazz.
So plenty to research and write about regarding his great early playing career.