I would love to see a non-terrible female DC hero in the group. It's cute that JLA's secretary has become an icon but I can't think of a dumber hero with lamer utilities who started as a female bondage heroine (not joking, look it up) for creepy men and "budding boys" to fetishize over. But bullet proof bracelets, a lasso (formerly the lasso of obedience FYI), "invisible plane" and boomerang Tiara? I'm sorry, but no. The only reason why people say she is a "must" is because she has been the token female superhero in the DC universe. That doesn't make her cool or a good call or anything.
Hawkgirl/woman, Zatanna, Black Canary, and even Vixen would be more interesting choices that are currently in the JLA. There's even female Green Arrows and Jade who is a Green Lantern.
Wonder Woman has got to be one of the laziest choices. She is the epitome of grandfathered in and I think it's a bit robbing of the rich world of female heroes to have her as the face of it. Either they made her into a secretary or they delved into the realm of ultra-feminazi (as in all men should die Amazonian philosophy, not the equality rhetoric that many people erroneously claim is "feminazism" when it's just fairness philosophy). The only reason a lot of men remember her fondly is the same reason that so many people remember the original Tomb Raider fondly. She was there, and voluptuous at important developmental periods of life.