It's a good question. Worldbuilding is a vital part of any fantasy novel, but I think similar themes will run through them all. Race, terrain, cities, possibly religion. I like to give the things in my world interesting and unusual names, including characters.
I've been reading the Mistborn Trilogy recently, and Brandon Sanderson has a world where ash falls like rain, which is pretty unique and interesting. But then when you read Lord of the Rings, it's set in pretty standard surroundings - forests, towns, mountains. The cities though are pretty unique and memorable. Minas Tirith for example, built into the side of a mountain.
I think the world you build ideally needs to have a purpose. For example, my novel Assassin has several different world, with a twin planet system. It's necessary for the story but I've also needed to make each planet unique, using terrain, weather and things of that kind.
Ultimately though, I think being unique is overrated. Most Novels follow a very small number of plots, with not particularly unique worlds. Whether it's successful will depend mainly on whether the characters have been written in a way that you care what happens to them.