Alyx Vance's Pragmatism
Alyx is one of the most beloved female characters in gaming for a reason. She's probably the least annoying NPC partner ever created; she always keeps her cool, makes jokes when they're needed, and knows when to shut up and fight. She's always got the tools for the job, whether that job is hacking alien computers or shooties zombies in the face, and she never loses her head.
Alyx is pretty close to being our perfect girl just based on those characteristics alone.