I agree with jewishboy regarding Kelli O'Hara and Marin Mazzie. I'm not a big fan of O'Hara--save for THE LIGHT OF THE PIAZZA. I don't think she looks like Mazzie or has any of Mazzie's great belt or her elegant flair. O'Hara is quite talented but Marin Mazzie is in a class of her own, IMO.
Having said that, Kelli O'Hara is not interchangeable like many of the girls listed on here.
I also don't think Laura Bell Bundy can be compared to Chenowetht. Whatever you wanna say about Chenoweth, she has immense star power when she's on stage...Laura "Bland" Bundy could be replaced by any generic blonde and I doubt anyone would notice the difference.
"Some people can thrive and bloom living life in a living room, that's perfect for some people of one hundred and five. But I at least gotta try, when I think of all the sights that I gotta see, all the places I gotta play, all the things that I gotta be at"