Yeah, Mystique may be the most recognizable name of Marvel's LGBT women, thanks to the X-Men movies (and the popularity of the X-line in general), but these days I wouldn't necessarily call her the most recognizable female LGBT character...at least not outside the main comic fandom. The comics have finally started acknowledging Mystique's bisexuality and referencing her relationship with Destiny again, but for the most part that aspect of her character has yet to be addressed in the movies, cartoons, games, etc. Karolina, Nico, and Ms America have all had their sexuality acknowledged in other media.
The other woman who might challenge Mystique for the most recognizable 'name' for an LGBT female at Marvel would be Black Cat--who is also finally having her bisexuality acknowledged in the comics again.