Better backstory?
Law's backstory is more melodramatic. Zoro's backstory, in its current state, accomplishes what it set out to do. Establish Zoro's goals and motivations, as well as inform his character and actions in the story. In some ways, it's a more efficient backstory than Law's, as it tells its story in far less time back when Oda didn't have the luxury of taking his time with them since he needed to keep readership engaged, or risk early cancellation. Oda has continue to add to it over the course of the series as well, and there's still room for another layer of it.
Cooler and more creative moveset?
This is all opinionated, since Oda does not really rely on combat and tactics as much as other Mangaka. Fights are merely a vessel for Oda to tell his story, and in that regard, Zoro's fights are engaging, because he fights not only for himself, but for his captain and late friend. In just the most recent fight, Zoro overcame his personal mental blocks and embraced his nature as a conqueror. A reversal of his development from pre-timeskip where his respect and loyalty for Luffy developed and he relinquished his pride and ambition in order to save his friends. Enma was the plot device which tested its will against his own. The drive he had first setting out to sea had to come back to the forefront in order win his most important battle yet and to reach the next step in his evolution as a swordsman.
Better design and clothing?
Very subjective. Starting with clothing, I like Zoro's attires far more. Aside from those that are great just aesthetically, like his Wano or Dressrosa looks (his Wano look especially for how authentic it makes him against the setting) -
-his default design marries the Western Caribbean pirate with an Eastern ancient samurai. That touch may become more complimentary once we learn more about Zoro's background and its ties to Wano, which we can expect a resolution on come Wano's end.
Basic design? Zoro has green hair, and is called a mosshead. I like green, and I find the nicknames given to Zoro to be adorable and enrich his character beyond the stoic badass he's intended to be. It lets his design standout, and leads to funny banter that are normally involved in relationships significant to him and that can show a different side. A side beyond his harsh exterior. A gentler soul who cares deeply for those around him, and those who can't defend themselves. On the other spectrum, his body is wracked with scars which tell us how much he has endured on his path to the top. It tells us that at the end of all this, he made it because of his determination, will power, and dedication to those he holds dear. That even hell itself could not stop him. Which is a reason why he now aptly calls himself "the King of Hell."