Are we ignoring the fact that the JLA/X-Men/Jedi wouldn't fight?
(This, BTW, is why I hate universe/crossovers.)
As for Superman being the most powerful: no.
The whole point of the JLA is that, however strong each of these heroes is alone, they're only unstoppable when they work together.
Superman's physical powers would give him an advantage over the Jedi: Although a lightsaber might be able to cut kryptonian flesh, he's physically stronger and faster than a Force-user, as well as being able to fly.
(And before the age-old debate reestablishes itself: JEDI CAN NOT FLY/LEVITATE. They can jump really high/far by using the Force to strengthen leg muscles, but they can't levitate themselves any more than you can pick yourself up by the collar.)
What S-man wouldn't have is a mental advantage: even his newfound torqasm-rao meditative skills are all "Sense" and "Control" based; he can't use them in battle the way a Jedi can use the Force.
The only JLAer who can match mental abilities with a Force-user would be Manhunter (Jonn J'onz), and he only has telepathy.
Batman's intellect would put him on even footing in a fight, but that's because Batman cheats. He would observe what the Jedi do, and conclude (correctly) that they are capable of manipulating an energy field. He would then find a way (assisted by Steel and Manhunter, most likely) to neutralize that energy field (ysalamiri or Force-cages).
Remember that Supes, Wonder Woman, and Manhunter are pretty evenly matched as far as raw strength goes.
"The Beasts know much that we do not." -Ancient Jedi proverb
[This message has been edited by BeastMaster (edited May 03, 2001).]