I've always supported ShinRan...they look cute together and just seem to fit. No, I have no particular reason for doing so. You have to admit, Ran's really loyal to Shinichi, I'd have a hard time waiting.
I'm positive that Haibara has a crush on Kudo, but I doubt that she'll let it grow in any way or form. I respect Haibara and I don't mind reading ConAi or being friends with people who support it, but I think of it more as a friendship than a girlfriend/boyfriend relationship. I can also kind of understand her feelings, falling in love with someone who's in love with someone else, and I sympathize with her. I'm glad that Haibara doesn't hate Ran and seems to try to keep her emotions under control. In fact, I love Haibara, I just don't really support ConAi since I find it somewhat difficult to imagine what would happen if the two were together.
Ran is really kind and everything, but she's also got flaws in many different aspects. Maybe it's the fact that she's somebody who's normal that stands out to me, she's not super smart and she really doesn't have a whole lot of unbelievable characteristics. I think that her loyalty and kindness are really the two characteristics that stood out to me a lot, and I admire her for it. I think that's why I'm a ShinRan.
Haibara is like snow, so cold, yet when you really get to know it, she's an amazing character. I respect and admire her, but I don't think she really fits with Conan. I think that Haibara is better off with an OC, though I admit that she should probably find someone who's just as intelligent. If you think about it, being with another boy who's a kid (a real one) wouldn't be too bad, Haibara never really got to experience a childhood, and it's only when she's around the Detective Boys that she truly warms up.