Erika's face is more vibrant. Her expressions are exuberant. I adore her colourful and sparkly eye-shadow as well as her magenta lips. Aqua highlights also looks nice on her brown hair.

Courtney
I like her Hair Style
And she is so kind ^^

Both are pretty, but Courtney is more sweet.

She's super gorgeous, I love her style. Plus I don't like Courtney's face cut that much...she's pretty too though. But I love that pop look of Erika!

Erika is prettier in my opinion.

She is prettier and her hairstyle is superb!

Both of them, but I prefer Erika more.

I love both! but specially erika and her hair

Courtney is a lovely and pretty princess, and an adorkable cinnamon roll (oops, too much Tumblr for me). I honestly can't say that Erika is 'pretty' because she's so unusually stunning for a Barbie character. I love both girls equally though, and they complete each other wonderfully (yes, I ship Courtney/Erika. Sue me, I don't care, I just love the idea)