As soon as Kelly Kapowski made her debut on Saved By The Bell, a large number of the audience knew that she was Zack Morris' dream girl -- even if the original episodes aired out of order. Though Zack and Kelly had many relationships throughout the show, they always got back together. This is largely because Zack continued to make his feelings for Kelly clear, even when he dated other people.
The two even ended up together, marrying in a movie special, and having a child in the sequel series. But was Kelly really the best match for Zack? There are a lot of characters he might have had a more interesting relationship with that could have made for a great happy ending for the series.
Lisa
Lisa and Zack could have made one of the best couples Saved By The Bell. The two knew each other pretty much their entire lives, and Zack was one of the first people Lisa would go to for help when she had a problem -- even knowing his track record of troublemaking.
The show briefly flirted with feelings between the two, but it never went farther than a kiss before dropping the storyline, which was a shame. The two learned a lot of the same lessons growing up about gossip, meddling in social lives, and being focused on material things. They grew together, which would have put them on equal footing in a relationship as adults.
Nikki
Fans of Saved By The Bell know that the first season was actually called Good Morning, Miss Bliss. The first 13 episodes were in middle school and Zack, Lisa, Screech, and Mr. Belding were the only characters to stay on when the series became Saved By The Bell. In these first episodes, though, Nikki is a lot like Jessie in the later seasons.
She and Zack don't agree on most academic things when they work together on school projects, but there's also nothing they wouldn't do for each other. Zack frequently ends up apologizing to her, without being prompted, in front of their entire class, which is a rarity for him throughout the series. The two share an interest in sports, like baseball, so despite their differences, there are also some things they have in common. Their friendship would have made a good foundation for a romantic relationship.
Kristy
Most of Zack's love interests didn't last more than a single episode that featured a single date that ended badly. Kristy is one of the exceptions. While she only went out with Zack during one episode, their story didn't end badly, leaving room for them to reconnect. But they never did.
Very different from most of the girls Zack dated, Kristy was someone who stood up to bullies for him rather than the other way around. She was a wrestler for the girls' team and she had no problem putting people in their place or using her wrestling skills to get bullies off Zack's back. A fun character who wouldn't have let Zack get away with anything, Kristy could have made a great long-term love interest.
Screech
If there's one person that is completely loyal to Zack and gets Zack's loyalty in return, it's Screech. While there were certainly sad things about Screech's character and troubling aspects to their friendship, but one thing is for sure, these two are inseparable and would do anything for one another.
In most stereotypical teen shows and movies, Zack and Screech would operate in separate social circles. There's something to be said for the two of them managing to stay best friends from preschool into their college years, despite their huge differences. There's also something to be said for the fact that Zack never intentionally hurt Screech like he did others. Some of his schemes put Screech in harm's way, but usually, Screech was his partner in crime, not the subject of it.
Jessie
Though Jessie and Slater's relationship is pretty volatile during the run of the show, hers with Zack is a little more affectionate. If the two of them could get past the fact that they dated each other's best friends, they could have made a good match.
For one thing, Zack actually values Jessie's opinion, unlike just about any other woman in his life. He comes to her for help on a regular basis when he's worried he's taken a step too far, like when he promises to get Screech a date and can't follow through. He also recognizes Jessie's insecurities and helps her deal with them, without judgment. It's Zack who gets her to participate in a dance contest with him when she's worried about being too tall compared to her potential partner. They supported one another without any serious judgment, a dynamic that was lacking amongst their friend group.
Leslie
Though most fans remember Kelly as Zack's main love interest for the run of the series, the Saved By The Bell: The College Years episodes did see him attempt a relationship with someone else: his suitemate, Leslie.
Leslie and Kelly actually aren't that different in their commitment to their education, their focus on honesty, their amusement at Zack's antics, and their need to be liked. The only reason Zack doesn't continue pursuing Leslie is because Kelly moves into their suite as well, bringing back all his memories of being high school sweethearts. If Kelly hadn't become a huge part of his college life, Zack could have seen where a relationship with Leslie could take him.
No One
There's a common thread amongst most of Zack's short-lived relationships in Saved By The Bell: he thinks a girl is pretty, so he pursues her, schemes to get close to her, and then those schemes usually blow up on him and he finds himself in trouble. It's rare that isn't the route he takes. Even when he gets to the point where he asks Kelly to marry him, he's still got a lot of growing up to do, and maybe doesn't actually need to end the series in a relationship.
In fact, Zack pressures himself into asking Kelly to marry him, only when he finds out she's going to be spending three months away from him as part of an academic program. He gets scared that she'll leave and forget him instead of trusting in the strength of their relationship. Zack really should have been on his own at the end of the series, taking the time to learn more about himself instead of focusing on the women around him.
Stacy
If there's one romantic relationship that actually seemed good for Zack during the show's run, it was with Stacy Karosi. The two didn't get along well, at first, primarily because Zack, as usual, wanted to take the easiest route possible for his summer job, and Stacy genuinely cared about her father's business doing well.
Despite them getting off on the wrong foot, they grew to respect one another, and Zack saw her as more than just a pretty face for a summer romance. Stacy didn't fall for Zack's schemes and didn't put up with his fake charm. She did, however, trust him to help her father. Zack, for his part, cleaned up his act around her and made a real effort to work hard and be her equal. They would have been perfect for one another.