Honestly?
Balalaika from Black Lagoon. She's as straight forward as a stick up an ass can be, and just as painful if you don't learn to properly deal with it. There's not much more to it than that. If she says something, she sticks to it. No BS, no cheap tricks, no vain threats. I find a serious lack of this archetype in anime, particularly in the position she's presented in. Balalaika's not the bad one just because the main characters have her favor, but if it wasn't that way...let's just say things wouldn't end up good.
Apart from that, the reporter archetype is usually a win/win to me. It doesn't matter it's position. Maybe he's just a (sparely used) sidekick as in Witchblade, maybe he's the protagonist as in Speed Grapher, maybe he's the bad guy as in some anime that I've probably yet to see or that is probably yet to fricking exist. For the simple reason that any character that follows this archetype well has this inherent "seek the truth" motivation that can lead to plenty of results and, if well handled, it can become a very good method to convey the plot without making it seem like hamhanded exposition. Problem is, these kind of characters are scarce, and it doesn't help that anime, in a fine lot of cases, has a serious issue with characterization.
EDIT: Those are the ones I like the most in anime. Out of that genre, I have a wider (and more permissive) array of favorites.