ShinRan.
I'm a sucker for childhood friends. If it weren't for that I'd be completely for ConAi.
Honestly, it's the relationship Shinichi and Ran had during their childhood. It has been developed so thoroughly that if Gosho (for whatever unlikely reason) decided to end the series with Conan and Haibara, it'd be a kick in the gut for both Ran, Shinichi, and many of the DC viewers.
Don't get me wrong, I can see why many support ConAi, and I'm not going to try to oppose their views, but the series just makes more sense if Shinichi and Ran end up together.