Part of this has already been posted at Xero Reflux Strikes Forum in the Ranma section of fanfiction.net, but there are things added and minor changes.
My views on who Ranma loves:
No one. He doesn't know what love is and has nothing to use as an example. He has a large crush on Akane but I don't think he actually loves her and I get the feeling that sometimes he hates her.
He may have loved his father sometime in the past but by the start of the manga he doesn't or at most he loves his father like an older brother you don't particularly like but respect.
He desperately wants to love his mom but he is afraid of her (with good reason the seppuku pledge even if she isn't serious about it he saw her dream about it and she did have him prepare for it). He tries so hard to please her because he wants her to love him and he wants to love her but as it is in the manga he doesn't love her.
As for the other fiancées and other people he may love them somewhat but no more than friends. Though he probably considers every single person he knows as his friends.
Who will Ranma marry? I don't know but Ranma doesn't seem to care enough about honor to marry someone that he doesn't love. Also Ranma is only 16 and does not want to marry anyone until he is older. Who ever Ranma does marry will have to get used to the fact that weird things happen around Ranma. Both Ranma and the person or people he marries (multiple people isn’t likely but the way Ranma’s life is wouldn’t really surprise many people) would have to first and foremost have to actually talk to Ranma. Many of the reasons that Ranma and his fiancées don't get along is because they don't really talk to Ranma. They rarely if ever bother to listen to Ranma or see things from his point of view. Ranma also doesn't bother to see things from their point of view either. Uyko, Shampoo, Kodachi, and Akane all have their own views as to what they're future would be like and never even ask Ranma what he wants. I doubt Ranma ever even really thinks about the future at all and I would make a bet that no one has ever asked him what he wants to do with his life.
Though now that I think about the person he would most likely marry would be Akane. My opinion though is if they married immediately after the manga or the wedding wasn’t interrupted it would be a very bad thing. Akane is definitely in the lead. She has several fairly large advantages over the other fiancees such as living with him, spending more time with him then the other fiancees, parents on her side, He has a crush on her (why I don't know but I think it has to do with how she was the first person to be nice to him in awhile and she occasionally tries and help him moreso than anyone else in the manga), longest engagement, being the first girl he even contemplated marrying, first memories of her aren't of her being a boy, trying to kill him, or paralysing him and leaving him helpless etc... I just believe that Ranma can easily go with someone else no matter what point in the manga even the exact end. It would not take a lot for one of the other fiancees or some other person to take the lead. He is also very possessive of Akane.
A few reasons Ranma doesn't pick anyone to marry are (Though I doubt Ranma spent much time thinking about these he would most likely know about and have thought about some of these at least in passing):
-Doesn't Really know what love is or loves anyone
-Too Young
-spends little to no time thinking of the future
-major intimacy issues
-Though Ranma and Genma may not care about this a lot if Ranma doesn't marry Akane (or a Tendo since the agreement never specified which tendo) he can be disowned by his family, be scorned by the community, as well as losing his rights to practice his particular school of Martial Arts (though Ranma would probably keep on practicing it anyways). I don't see Gemna disowning Ranma (may threaten to, to get his way) but Ranma's mom might. Of course she might just tell Ranma to kill himself or marry Akane.
-Doesn't know for sure that any of them actually love him and Ranma does not want a loveless marriage. EX. Is Shampoo doing it because of her village laws or because she loves him? Yes the reversal jewel shows that she loves him but does Ranma know that (we don't know what if anything Ranma was told by cologne about it and we don't know if Ranma believed her or not).
-His curse. Ranma sees his curse as a disability. Whether it is or isn't Ranma sees it as one. Disabilities are looked down upon in Japan in general and Ranma may consider it to be an obstacle to a happy marriage. This one can be backed up by the manga because Akane always calls Ranma a pervert and sometimes it's only because he's a boy who can change into a girl. In volume 8 Akane says during the time Ranma is trying to get into the girls locker room to get the Japanese spring of drowned man "and I used to think only your body was sick and twisted..." You know people are always saying how Ranma says cruel things well Akane says a lot of really cruel things as well and in my opinion the cruel things she says are generally worse than the ones Ranma says.
-Amazons. The amazons are a major threat. If Ranma married someone besides Shampoo what would the amazons do? Ranma knows that the amazons have magical items, ki techniques probably some he doesn't know, and has pretty harsh laws. Shampoo has shown that she can be pretty ruthless, if Ranma married someone else would the Amazons/Shampoo kill the person he married and brainwash him so that he didn't even know that he had gotten married? (Personally I don't see this as overly likely but is cannonly valid.)
The following Ranma is even less likely to have ever thought about but he may have.
-Shampoo was punished by being thrown into Junsenkyo for not killing Ranma what punishment if there is even a punishment would Shampoo get for not marrying him. (Personally I don't believe there is a major punishment because the amazons most likely won't force Amazons to marry someone against their will and if they did then it's most likely have a kid to bring the genes into the tribe then dump/kill/brainwash the person.)
-Uyko. If Ranma doesn't marry her what would she do? Go back to trying and kill Ranma. Kill the person he marries. Maybe even get depressed and kill herself. I don't think Uyko would kill herself but Ranma's sometimes arrogant enough to think she might if he didn't marry her. (Ranma isn't arrogant all the time sometimes it is shown that he has low self-esteem and he is occasionally humble.)
-Akane. Ranma has seen and noticed that Akane gets jealous. As well as hits him when she is angry. What reaction would Akane have to him marrying someone else?