I'm kind of being serious here, but what character? Chell is a voiceless soulless automaton without any personality.
I certainly can't speak on Anita's behalf, but Chell passes the shockingly low standard of just not being a shitty trope of some kind. She's not running around in heels, she doesn't have any vocal quips along the lines of "Bet you didn't think a girl could do that," she wasn't created as an object of male wish fulfillment, and she also happens to take an active role in the story. Chell is the one that realizes the reality of the situation she's in, Chell is the one that overcomes GLaDOS and escapes, etc.
I personally think that GLaDOS is a better character, for what it's worth. Beyond being very funny (female characters rarely get to be funny in games), she has a clearly expressed personality that fleshes out her motivations, as simple as they are.