I'd go with a two-way tie between Princess Zelda and Jen Mui (from the Mercenaries series). The first one is always playing hard-to-get (to the point of total frustration sometimes), and the second one cares only about money (really, she'd kill you and blow up the rest of the returant if someone would pay her. Also, as a word of warning, don't piss her off, because it's important to remember, everybody pays...).
Some other [not-so-bad] choices would include (these would be the people you would write off as "maybe", not "Never Ever"):
- Bastila Shan, from KotOR (at first, but I guess she's not so bad when she opens up)
- "Ms. July", from Battlefield: Bad Company (we never find out what she looks like, but at least she shows that she cares for her friends)
- Any Female lead from KotOR II (Visas and Brianna aeem to keep to themselves, and they take a while to warm up to anyone; Mira is a wolf in sheep's clothes, she's much more likely to hit you in the back of the skull with a stun baton that accept a date)
- Samus Aran, from the Metroid series (sure, she's wiped entire planets of life before, but at least she seems mature and in control of herself at all times)
- Any female character from the Command & Conquer (Red Alert sub-series in particular) series (they look the part, but they all seem to be insane..)
There are probably some good choices, but that would be a seperate thread, now wouldn't it?