Mustafar is the planet where Anakin Skywalker was burned from the lava and turned into the Sith Lord Darth Vader. It is very important in the saga, and it is also where Vader lives.
This planet is very similar to Tatooine, but it is not. It is called Jakku. Jakku is important because it is where Rey grew up. She lived in an old AT-AT out on its own, laying down in the sand.
Hoth is an icy, cold planet. In the Empire Strikes Back, Hoth is where the Rebel Base is located. Of course, it is where the Battle of Hoth took place. So it is a very important planet.
In the Phantom Menace, Padme Amidala is Queen of Naboo. But in Attack of the Clones, she is now a senator. Of course, it is where the Battle of Naboo took place, and it is an important planet in the saga.
Tatooine is the best and most important planet in the history of Star Wars because it is home to almost all the Skywalkers, from Anakin to Luke. Like Jakku, it is covered with sand as far as the eye can see.