Tara Strong got my vote. Highly underrated voice actress. I mean, just look at the range in her roles!
I'm not sure if there is any role she couldn't do, short of adult males.
Bubbles in "Powerpuff Girls"
Harley Quinn in "Batman: Arkham City" and the upcoming "Injustice: Gods Among Us"
Raven in "Teen Titans" and the upcoming "Injustice: Gods Among Us"
Twilight Sparkle in "My Little Pony: Friendship is Magic"
Timmy Turner in "Fairly Oddparents"
Sari Sumdac and Slipstream in "Transformers Animated"
Princess Clara and Toot in "Drawn Together"
Harley Quinn in "Batman: Arkham City" and the upcoming "Injustice: Gods Among Us"
Raven in "Teen Titans" and the upcoming "Injustice: Gods Among Us"
Twilight Sparkle in "My Little Pony: Friendship is Magic"
Timmy Turner in "Fairly Oddparents"
Sari Sumdac and Slipstream in "Transformers Animated"
Princess Clara and Toot in "Drawn Together"
I'm not sure if there is any role she couldn't do, short of adult males.