I would say either Nellie and Percival or Mary and Adam. Those two couples seemed to get along well and were happy most of the time. I am still single, but I know that I want a marriage like Nellie and Percival and/or Mary and Adam.
Nellie and Percival: They were very much in love, and both respected each other. Their marriage seemed to be an equal partnership with an equal amount of give and take from both. Marriage should enhance your life, meaning that if you decide to get married that you should be even happier than you were when you were single. That was certainly the case with Nellie. Before Percival, she was miserable most of the time. Once Percival joined her life, Nellie enjoyed life in a way that she never had before. They were a great couple!
Mary and Adam: Just like Nellie and Percival, their marriage was an equal partnership based on mutual love and respect. Both went to bat for the other. For example, Mary convinced the professor to let Adam complete the law exam because she knew how much it meant to him. Likewise, Adam shielded Mary from being hurt by his father after she miscarried the baby. He had to be a little untruthful, but it was to protect her. The only time they had major conflict was the transition period when Adam regained his sight, but they worked that out.
The above two marriages are the only two on this show that I would like for my marriage to be like. Let's examine the others.
Charles and Caroline: Yes, they were very much in love and shared a lot of happiness. But, Charles was always getting into fights and getting hurt, and that was annoying. Caroline could be a bit clingy and acted like she would lose her mind whenever Charles had to be gone. Charles never minded his own business on anything. Another thing that annoyed me about Charles was the way he would cut Caroline off if she was about to say something in a tense situation. For instance, the time Laura was late and had them worried, Caroline started to say something. Charles cut her off with, "Caroline, I've looked everywhere. We have to wait!!!". Things like that drove me nuts.
Nels and Harriet: They were actually happy most of the time, and yes, they did definitely love each other. Even though they got on each other's nerves a lot, that one episode demonstrated that they couldn't live without each other, and that they actually liked each other the way they were. Not the type of marriage I would want, but to each their own. If the couple of happy, that's all that matters.
Isaiah and Grace: They were happy in the beginning, but Mr. Edwards was actually better being single. It's not just that his alcoholism eventually destroyed his marriage, but he could have a really bad attitude on things. He treated Grace and his family badly after his accident and was close to suicide. He treated John, Jr. terrible just because they didn't see eye to eye. He also always seemed to get his feelings hurt. Mr. Edwards had a lot of good qualities, but married life never seemed to work for him.
Johnathan and Alice: They had a decent marriage, although Johnathan could be immature at times. Him not wanting Alice to work was annoying, but he came around in the end. They also nearly got divorced over a stupid argument. All in all, pretty good marriage based on love and respect. Too bad Alice died.
Laura and Almanzo: The marriage of two immature, childish idiots!! When one wasn't acting immature, the other one was. Sometimes it was both. Almanzo seemed mature during the time before he and Laura got together, the time period when she was still a kid. I guess his true colors came out later, and we see how immature he is. He acted like a total fool by not wanting Laura to teach to help make money. Was he the only one who mattered? Laura was equally foolish when she attacked Brenda Sue in the street- in front of her schoolchildren!! That's good teacher, show those kids how it's done! In that episode, Laura seemed to forget that she was married, and that her life was not just her own anymore. Almanzo shouldn't have been banished outside to play his guitar. This couple got better as the years went on but still.