I like her on Chicago Fire
To me, she stands out because, while she's a lovely woman like most women on TV are, her face has this expressiveness (I want to say "plasticity") that makes her a natural for a lot of the comedic material as well as holding her own with the drama. She can bust out the goody grins and the raised eyebrows and - to me - really connects to the viewer.
May not translate to other work, but for this show she has a nice vivid presence that's noticeable.
btw, I love Kara Killmer on CF, but she's a lot more low-key when it comes to facial expression.