Although I didn't like it at first, extended viewing has convinced me that DS9 is the most well-written out of all the Star Trek's, probably to compete with the also-excellent Babylon 5. Characterization is slow and steady, but the arcs are large (although not as large as B5). The characters themselves are noble but imperfect, making them easy to misunderstand but sympathize with at the same time.
And what's irrelevant about Enterprise? It's got sexual innuendo, nude aliens, wise-cracking aliens, a theme song that Five For Fighting will probably remake, and scriptwriting gems worthy of Xena ("I think he likes you pink skin!"). What else could viewers nowadays want? Enterprise = Deep Space 90210.