Superman - Superman done right is great stuff, but he's rarely, if ever f=done right in JLA. Pass.
Wonder Woman - She's always just the token powerful female. I hear Rucka's doing wonders over in her ongoing, but in JLA she pretty much hangs out and taunts the guys. Pass.
The Batman - Ugh. I'm not even going to go into why Batman shouldn't ever join the JLA, plus Morrison's portrayal of him in it helped bring us to the current Uber-Bat of today. Pass.
Green Lantern - Passed only because the GLs of the JLA have been John Stewart and Hal Jordan lately. I'm a Kyle Rayner/Guy Gardner lantern fan. The other guys are pretty stiff characters.
The Flash - I love me some Flash. In the past 20 years DC has done an excellent job of turning a once sidekick into a grade A superhero. He's getting my vote.
Martian Manhunter - I really like J'onn J'ozz. He's got alot of untapped potential, but his inability to carry an ongoing outside of JLA hurts him. What'd be nice is if they'd go back to useing him in Detective Comics backups like they did when he came out. Close, but isn't beating The Flash.
Green Arrow - Now, I think he had the perfect death, then they went and brought him back, with some unkown hack writing it at that! Phft. Pass.
Plastic Man - Too damn silly. Alot of fun though. Pass.
Aquaman - Now Morrison managed to make Aquaman cool in his run, wich is impressive. Not cool enough to get my vote though. Pass.
Captain Marvel - Caps got a decent enough history to be on the list, being a founder of the post-Legends Blue Beetle/Booster Gold JLA, but he's much more closely associated with the JSA anymore to get my vote.
And wheres our Firestorm or Zatanna?