I would say 'The Courtship of Princess Leia' is a great read. It has an interesting story about Han Solo competing with another suitor for Leia's hand in marriage. It has elements of adventure, politics, and of course, the classic Star Wars romance.
Definitely 'Thrawn: Alliances'. It gives more depth to the character of Thrawn. It also has some great interactions between Thrawn and Darth Vader, which is really cool to read as it shows two very different but powerful characters from the Star Wars universe coming together.
Definitely 'Heir to the Empire'. It was a huge deal as it continued the story after 'Return of the Jedi' and reintroduced many beloved characters in new and exciting situations.
The 'X - Wing' series, especially books like 'Rogue Squadron'. It focuses on the pilots in the Star Wars universe. It gives a great look at the military side of things, the camaraderie among the pilots, and their exciting battles against the Empire.
Another good one is 'Darth Bane: Path of Destruction'. It delves into the origin of the 'Rule of Two' in the Sith order, which is a crucial part of the Star Wars lore. It gives a lot of depth to the Sith side of things.
Some of the highly regarded ones are 'Heir to the Empire' by Timothy Zahn. It really expanded the post - original trilogy universe and introduced great new characters like Grand Admiral Thrawn. His strategic mind and the complex plots made it a classic.
Episode 10 is a great one. It delves deep into the backstories of some lesser - known characters in the expanded universe.
Another notable one is 'Darth Bane: Path of Destruction'. It explores the origin of the Rule of Two in the Sith order, which is a very important aspect of the Star Wars lore. It gives a detailed look into the Sith ideology and how it evolved over time.
I think 'The New Jedi Order: Vector Prime' was not great. It was the start of the Yuuzhan Vong invasion arc, and while it had potential, it just didn't quite hit the mark. The new villains were hard to understand and not as engaging as the classic Sith or Imperial foes.
One of the highly regarded expanded universe Star Wars novels is 'Heir to the Empire' by Timothy Zahn. It introduced great new characters like Grand Admiral Thrawn and really expanded the post - 'Return of the Jedi' universe in an exciting way.
One of the worst could be 'The Crystal Star'. It had a convoluted plot that didn't seem to fit well with the overall Star Wars feel. The characters' actions and development were rather strange, and it was hard to get into the story.
One of the top stories is 'Thrawn Trilogy'. It introduced the brilliant Grand Admiral Thrawn, a very interesting villain. His strategic mind and unique leadership made the story engaging.