* gut: This is the most common and general word for "good." It's suitable for most situations.
* nett: This means "nice" or "kind," and is used to describe people or things that are pleasant.
* fein: This means "fine," "excellent," or "great," and often implies a higher level of quality than "gut."
* prächtig: This means "splendid," "magnificent," or "gorgeous," and is used for something exceptionally good.
So, the best translation depends on what you want to say. "Gut" is a safe bet for most situations.