JK Rowling is the author, so I'm sure she knows best, but I totally see Ron and Hermione together. I think their opposite natures complement each other. Maybe Ron doesn't always pay attention and isn't a bookwork. Hermione is smart and dedicated to knowledge. She has a know-it-all personality sometimes. That's what makes her such a great character. Ron's more laid back style balances that. I think they helped each other grow throughout the series, and they would have kept doing so after. I don't think it's always true, but sometimes opposites really do attract and can be good together.
I loved that Harry and Hermione were always friends first, and I never got the vibe that they really ever thought about being more. The books are far better than the movies, but I loved the scene where Harry and Hermione are alone after Ron leaves, and they dance in the tent. There may have been a split second that they would have contemplated being more, but that wasn't their destiny. In today's world, there aren't a lot of times girls and boys can truly be just friends without drama, but I always thought Harry and Hermione were able to keep things platonic successfully. I loved that about them.
So, JK Rowling may have done things differently if she were to write the series all over again, but I think things turned out the way they should have.
Any different opinions? I'll keep an open mind :)