I am always reluctant to single out some particular feature of the work of a major filmmaker because it tends inevitably to simplify and reduce the work. But in this book of screenplays by Krzysztof Kieslowski and his co-author, Krzysztof Piesiewicz, it should not be out of place to observe that they have the very rare ability to dramatize their ideas rather than just talking about them. By making their points through the dramatic action of the story they gain the added power of allowing the audience to discover what's really going on rather than being told. They do this with such dazzling skill, you never see the ideas coming and don't realize until much later how profoundly they have reached your heart.
Cowboy Bebop: The Movie (★★★★)
The movie can be seen as taking place before the 22nd and 23rd episode, or even after the series; the film was made after the series and should be seen afterwards to avoid messing up the pacing of the series.
Seinfeld is worth watching even if you hate laugh tracks. After the show you should watch Curb Your Enthusiasm starring and written by Larry David, who wrote most of the episodes. Season 7 of Curb is about him directing a Seinfeld reunion, and you should at least watch the fake Seinfeld reunion.
The first season of Deep Space Nine occurs during the end of The Next Generation and there is some story overlap: Wikipedia has the chronological viewing order. The series won't be less enjoyable if you already watched the entire TNG series.