Captain Jack Harkness says hello.
So do Captain Jack Sparrow, Tony Stark, Dean Winchester, Faith from BtVS, Gambit, Nightwing, Chiana, Hawkeye Pierce, and the inestimable Phryne Fisher. That's ten characters just off the top of my head. All have slutted around their respective canons while remaining popular with their audiences, often more so than their less promiscuous peers. As have our own dear Isabela, Zevran and the Iron Bull for that matter. We're even starting to see more promiscuous women portrayed positively!
(I'm using 'slutted around' in a positive sense here, were that not clear.)
I'm personally not a major fan of any of those characters, although I'm not sure where you get the impression Jack Sparrow screwed around a lot. Sure he was drunk and leery but tons of sex? Who knows.
I think most of the characters you mentioned have critical success only after they blended with Hollywood to be honest, on their own terms they're still kind of niche comic things mostly, major comic canon characters sure, but still comicy and I sort of view their pre-eminence as this bizzare alliance between major Hollywood and and so on that doesn't make me feel like these things are arising naturally but are rather like Frankenstein sort of stichted together/hybrid conection.
I also didn't particularly like Isabela, Zevran, or Iron Bull.
The only characters I like are basically like Adjantis, Kivan, BG1 Minsc and Imoen, and honestly Edwin as well, BG2 Jaheira, Viconia, and a few other BG1/BG2 characters (definitely not Aerie, Nalia, Cernd, Anomen, everything after that I don't really see as on the same level. ToB Sarevok is cool and honestly I think the enemies in the game are pretty impressive (Balthasar, Melissan) I mean it's mostly the BG1 characters I'd have to say. In terms of other games (non-Japanese) it's mostly Jaina Proudmoore, Sylvannas Windrunner, Uther Pendragon, and a handful of other WC2/WC3 characters.
In terms of a KISA character I'm pretty sure Keldorn is pretty close.
I want to say perhaps a few of the companions from Torment or Fallout 2, and perhaps a few from the second Witcher game.
I mean even NWN (and HotU) Aribeth was better than any DA character frankly.
Whenever I bring those up though people refer to the fact that those characters were mostly an accident of the limitations of technology, but regardless of the origins, they seemed to have a kind of impact I was thinking of in this particular context, I mean really, sex scenes in Baldur's Gate 1? This was a different time and place apparently, free from the excessive fan-fiction driven fantasying ownership scenario that seems to happen in modern games where characters are designed primarily to fuel particular sexual lusts or fantasies.
This modern we're going to make a this character, a that character, a bisexual strong knight character or whatever it is, is not impressing me in the slightest, it's generally speaking going to be a character similar to whatever that company/creator makes generally, but with the labels changed around.
Heck the strongest female character character I played was probably the thief/ninja character in Kingdom Rush, which is a freaking tower defense mobile game.