In The Catcher in the Rye, Jane's one trait that Holden continually talks about is her habit of keeping all of her kings in the back row while playing checkers. This is just symbolic of the larger reason why Holden likes Jane: he sees her as an individual, not just a sex object.
Contrast Holden's feelings about Jane with Stradlater's. When Holden keeps asking his roommate whether he asked Jane if she still keeps her "kings in the back row," Stradlater responds, "What the hell ya think we did all night—play checkers, for Chrissake?" Holden then begins to obsess with the date Jane goes on with Stradlater and worries he gave her the "time" in the back of Ed Banky's car.
There are many other characteristics Holden likes about Jane. He likes that she can hold hands during a movie "and wouldn't quit until the movie was over. And without changing position or making a big deal out of it." He even talks about how she, like him, seems to be a bit broken, as she suggests her stepfather might be abusive, sexually or otherwise.
For Holden, Jane is genuine, while his other love interest, Sally Hayes, is phony and into all the things adults say you have to have in order to be successful.