Of the three live-action Supergirls, I think the best-looking one was Helen Slater. Though my favorite overall, in looks and personality, is the DC Animated Universe version designed by Bruce Timm.
Looking over IMDb's character page for Supergirl, it's surprising how rarely she's been adapted to the screen compared to a lot of other DC characters. There's Helen Slater's movie in 1984, then nothing until she shows up in Superman: TAS in 1998-2000 (played by Nicholle Tom), and later returns in Justice League Unlimited from 2004-6. Then there's Laura Vandervoort in Smallville (not counting Adrienne Palicki as the fake Kara several seasons earlier, since she was a human hypnotized by Jor-El's ghost for nebulous reasons). And then two DC Universe DVD movies, Superman/Batman: Apocalypse (voiced by Summer Glau) and Superman: Unbound (voiced by Molly C. Quinn). Then there's the Super Best Friends Forever DC Nation shorts (voiced by Nicole Sullivan), and now there's this pilot. That's only seven different screen Supergirls in the entire 56-year history of the character, and none at all until 25 years after her creation.
Compare that to Batgirl, her closest counterpart. For her we've got:
Yvonne Craig, Batman (1967)
Jane Webb, The Adventures of Batman ('68), and Melendy Britt, The New Adventures of Batman ('77)
Melissa Gilbert, Mary Kay Bergman, and Tara Strong, DC Animated Universe ('93ff) -- also Stockard Channing and Angie Harmon as Commissioner Barbara Gordon in Batman Beyond
Alicia Silverstone, Batman and Robin ('97) -- borderline, since she wasn't Barbara Gordon.
Dina Meyer, Birds of Prey (2002)
Danielle Judovits, The Batman ('05)
Mae Whitman, Batman: The Brave and the Bold ('10)
Tara Strong again, Super Best Friends Forever ('12)
Alyson Stoner, Young Justice ('12)
Tara Strong yet again, Beware the Batman ('13)
Tara Strong one more time, Teen Titans Go ('13, cameos)
Unknown, TNT Titans pilot (not yet made)
Also there's Jim Gordon's unnamed redheaded daughter in Batman Begins and The Dark Knight, implicitly Barbara, and played by two different child actresses.
So Batgirl and/or Barbara Gordon has nearly twice as many screen incarnations as Supergirl, played by at least twice as many actresses. And her first screen appearance was no more than a year after her comics debut, rather than a quarter-century later.
Well, I guess it reflects the relatively greater popularity of Batman over the past half-century. Superman was huge in the '40s and '50s, but the '66 series put Batman in the spotlight. Superman had a resurgence with the Reeve movies, but that fizzled out, and then Batman came back huge in '89 and has been on top ever since. So by the time Supergirl came along, Superman's heyday on screen was fading. While Batgirl has benefitted from Batman's perennial popularity.
Looking over IMDb's character page for Supergirl, it's surprising how rarely she's been adapted to the screen compared to a lot of other DC characters. There's Helen Slater's movie in 1984, then nothing until she shows up in Superman: TAS in 1998-2000 (played by Nicholle Tom), and later returns in Justice League Unlimited from 2004-6. Then there's Laura Vandervoort in Smallville (not counting Adrienne Palicki as the fake Kara several seasons earlier, since she was a human hypnotized by Jor-El's ghost for nebulous reasons). And then two DC Universe DVD movies, Superman/Batman: Apocalypse (voiced by Summer Glau) and Superman: Unbound (voiced by Molly C. Quinn). Then there's the Super Best Friends Forever DC Nation shorts (voiced by Nicole Sullivan), and now there's this pilot. That's only seven different screen Supergirls in the entire 56-year history of the character, and none at all until 25 years after her creation.
Compare that to Batgirl, her closest counterpart. For her we've got:
Yvonne Craig, Batman (1967)
Jane Webb, The Adventures of Batman ('68), and Melendy Britt, The New Adventures of Batman ('77)
Melissa Gilbert, Mary Kay Bergman, and Tara Strong, DC Animated Universe ('93ff) -- also Stockard Channing and Angie Harmon as Commissioner Barbara Gordon in Batman Beyond
Alicia Silverstone, Batman and Robin ('97) -- borderline, since she wasn't Barbara Gordon.
Dina Meyer, Birds of Prey (2002)
Danielle Judovits, The Batman ('05)
Mae Whitman, Batman: The Brave and the Bold ('10)
Tara Strong again, Super Best Friends Forever ('12)
Alyson Stoner, Young Justice ('12)
Tara Strong yet again, Beware the Batman ('13)
Tara Strong one more time, Teen Titans Go ('13, cameos)
Unknown, TNT Titans pilot (not yet made)
Also there's Jim Gordon's unnamed redheaded daughter in Batman Begins and The Dark Knight, implicitly Barbara, and played by two different child actresses.
So Batgirl and/or Barbara Gordon has nearly twice as many screen incarnations as Supergirl, played by at least twice as many actresses. And her first screen appearance was no more than a year after her comics debut, rather than a quarter-century later.
Well, I guess it reflects the relatively greater popularity of Batman over the past half-century. Superman was huge in the '40s and '50s, but the '66 series put Batman in the spotlight. Superman had a resurgence with the Reeve movies, but that fizzled out, and then Batman came back huge in '89 and has been on top ever since. So by the time Supergirl came along, Superman's heyday on screen was fading. While Batgirl has benefitted from Batman's perennial popularity.