1. Constitution-class: This includes both the classic Constitution-class and the later refit variants. They are renowned for their iconic saucer separation, which was seen in several episodes of the original series.
2. Galaxy-class: This includes the standard Galaxy-class and the Galaxy-X variants. While not as famous as the Constitution-class for it, they also feature the ability to separate their saucers.
It's important to note that the ability to separate the saucer is a game mechanic and does not necessarily reflect canon.
Other ships in the game that are not capable of separating their saucers, despite having a similar design, include:
* Excelsior-class: Even though it has a distinct saucer section, it doesn't have the ability to separate it in-game.
* Nebula-class: This class also features a separate saucer but lacks the gameplay feature of separation.
If you're looking for a ship with this unique ability, the Constitution-class and Galaxy-class are your best choices in Star Trek Online.