Shinichi would make sense to me whether is was ShinRan, ConAi, or ConAyu to be honest.
ShinRan --> It's obvious?
They are both dedicated, make a wonderful team, and it's not ALL mushy love. Shinichi only has his eye on Ran, he's got plently of girls to choose from but he chose Ran. Since Volume 1 it was obvious he already liked her and after years of DC he still does. Ran on the other hand is also just as dedicated. Though Conan resembles Shinichi and she's had her doubts, to her Conan and Shinichi ARE DIFFERENT PEOPLE. But she continues to wait and believe in him. Most girls would just question everything to the point they'd throw their hands up and give up on hope. Ran firmly believe in Shinichi. Trust. They share that. Secondly, they make a great team. Shinichi is a highly intelligent and athletic while Ran is the sweet and loving kind. How does this work out? Well, think about it as Ran filling up the holes. Shinichi maybe be the oh-so-great-detective. But his cooking skills are as good as Heiji's. Not a good thing. Ran is cable of that subject however, she takes care of Conan and her father. Cooking &cleaning with an optimistic attitude. Besides, Shinichi LOVES her lemon pie best *wink wink*. So they make a great team because they have each other's backs and they can cover for each other's "weaknesses" if you want to call it that. Now this "MUSHY LOVE" doesn't have to really do with anything, but it's a quick point I'd like to make. People often get the wrong idea that they're a 'fairytale' &'run into your arms' couple. WROOONG. They act like best friends when together but on the inside they have a sense of BOTH admiration and attraction. What I mean is that they Ran and Shinichi don't JUST get all mushy and cheesy. That's behind the scenes with their TRUE feelings. Their interaction is more playful, Volume 1 once again. Ran does like Shinichi but she doesn't cling to him, she plays around with him, 'a chase' as they call it. Anyway enough of them, moving on...
ConAi--> It DOES make sense
Conan and Ai does make sense to me. Conan may realize that Ai is the one for him. It's all possible. Now I personally DO think Ai has SOME feelings for him at the very least. He's shown her kindness and comfort, something she lacked in her life. Ai has made Conan a better person despite the fact that she never intended to. They've got SOME chemistry going on, I can admit that much. But what I DON'T like about this pairing idea is that Ai might actually not like Conan at the same time. Conan was first to show her kindness, great. But I think that Ai is more like taken by admiration. He's more like the hero that saved her from the dark pits of BO. He's supported her. She also feels better around him because he's going through the same thing on terms of "shrunken adults". Also, another thing, I don't think Ai was actually go for Conan despite her feelings. She's aware of both Ran and Shinichi's feelings towards one another, as well as Ayumi's feelings towards Conan. I don't think Ai would even try to take Conan and end up hurting both Ran and Ayumi, they're practically the closest females to her. Ran reminds her of her sister Akemi, and Ayumi is very sweet and they get along well. Would Ai really hurt them both to get Conan? I think not, Ai is better than that, she'd put her feelings aside for others in my opinion. She wants the best for others, that why she used to want to hide. To protect those around her. Bus incident? Nearly SUICIDED for the sake of everyone else?! Yeah. Besides *I* personally think she'd be better off with Mitsuhiko *cough* Moving on...
ConAyu--> Also DOES make some sense, to en extent.
Anyone ever notice how Ayumi is sorta like a mini Ran Mouri? Well if Gosho WAS ever evil enough to prevent Conan from turning back into Shinichi then this is also an option. Conan might just slip into that state where he feels so hopeless he goes for his next best choice. Ayumi resembles a mini Ran . An this is also if Ai doesn't deicde that she wants to tell Conan she loves him. And if this wasn't considered pedophilia in ways. Not my strongest pairing. So if these circumstance were ever fullfilled ConAyu does have its slim chances? It makes sense. TO AN EXTENT. Yeah. Still if Conan could never turn back I picture him still with Ran after he re-grew up. Ran excepts him and they still could get a sorta happily ever after. It reminds me of Kagome &Inuyasha in that case (You know, Conan just 'happens' to be exactly like Shinichi? And Ran could fall for Conan anyway?). Simple because by then even if Conan fesses up that he'd actually Shinichi, Ran probably won't believe him any longer, (OVA 9 reference ). Ok enough of the ranting. My answer ..
So if you haven't guessed it yet, I'd still support ShinRan to the bitter end. And I do think Ran is more suitable for him anyway (Filling in the 'holes'). ConAi is understandable, I just don't really like it and I can find some flaws in the idea (And because maybe I'm the only one who thinks it's messed up for Shinichi to fall in love with the girl who stopped him from being able to love his first, ORIGINAL love, Ran? Just saying.) . I know that Ayumi isn't a choice in the title or poll but I just though I'd throw that in there. Yeah SHINRAN \o/
Congrats the person who actually reads through all of that...
Enough rambling for today, I'll be back for more on another rainy day ~