Of the stories I've finished reading, the ones I like the most are SIGN and SCAN. That's probably because in SIGN, Watson meets his future wife, and in SCAN, Holmes meets "the woman." Yeah, I'm a romantic at heart, can you tell? Still, I don't think Holmes loved Irene Adler. I think it was more admiration.
My OC love interest for Sherlock has a name, a personality, a family, and an appearance. I'm toying with various ideas for her occupation. And of course, she has a problem for Holmes and Watson to solve.