Second much of the above, but if you really want to see onscreen development it's Kira/Visitor, who visibly grows and stretches as an actor and character from the pilot to the finale arguably more than any other.
Ds9 was a exciting and dangerous place with its own energy. Who wouldn't want to stroll the Promenade and have a few drinks at Quarks? Then maybe visit Bajor and see an orb. I think the reality of the world of DS9 is its greatest appeal. Kudos to Berman, Piller, and Behr.
This is a little bit of what has kept me away. I love TNG for it's idealistic vision of the Federation and the future. I didn't appreciate Enterprise or Discovery as much because they focused more on conflict, and are a little "darker" and more realistic. Which I don't mind in other types of TV I watch, but to me Star Trek is best when it's idealistic and has a positive vision of the future. That said, I'll likely give DS9 a shot, especially since it sounds like there are some great characters.
One thing that I appreciate about DS9 is that there are entire episodes where Sisko is barely seen. How many TNG episodes do we have where we don't see Picard a lot, let alone TOS and Kirk?
Ds9 could often be very warm and fuzzy. The relationship between Jake and Benjamin Sisko was the most intimate father-son relationship portrayed in Star Trek. The Bashir - O'brien friendship was a great bromance, which also injected warmth to DS9.
Amen. The Siskos are arguably the most functional family in all of STAR TREK. Everybody else is estranged from parents, brothers, sisters, long-lost children, etc. Proving that even when we've conquered war, poverty, and prejudice, families still drive people nuts.
The only thing DS9 ever had going for it was the characters and the relationships. Everything else about it - aside from maybe the promenade set - was unremarkable. Exactly. It wasn't 'dark and gritty' so much as it was silly and puerile and trite and not at all worth taking seriously. It's like the ten-year-old who swears every other word thinking it makes him sound like a grown-up. But he really just sounds like Spock in a bathrobe.
They succeeded in creating a very immersive environment where you almost felt like you knew what was around each corner of the station and would run into someone you wanted to see. It took on diversity and unity in nuanced ways, and made an old space station into a home. It was a good balance of development for main characters as well as side characters. And they didn't always talk themselves out of an epic battle scene at the last minute. Gritty, but also kind and moving.
Whenever I compare DS9 to TNG or do a re-watch, I notice some important differences. Episodic shows like TNG all start and end the same way. The intro, the plot, and the resolution at the end. By next week's episode, no matter how serious it was, it's usually forgotten and never mentioned again. It leaves the characters with a two dimensional feel to them. It was also little too idealistic (IMO). These characters had no conflict, never cursed, got drunk, or did off color things. The entertainment was watching plays, a classical concert, poetry readings, etc. It was really stuffy at one point. And then there's dialog. In a way it's kind of stilted in TNG, because it always revolves around the plot. In DS9, the dialog is complex because the characters themselves are more serialized. So they mention things, relationships, arguments, or whatever that happened a week or month or years ago. They were more opinionated, unpredictable, did shades of grey things considering the part of space they were in, and brought up the past a lot. Or told off color jokes (waste extraction). It had some pretty off color and serious episodes like the separation of church and state or war criminals. Or the Maquis/terrorist thing. TNG did do similar episodes, but DS9 seem to do them in more complex and attention-getting ways.
It broke the mold or format of a ship going where no man has gone before, and proved that you could still do a Trek series without that. I wouldn't say the series got rid of the alien-of-the-week format, you still had alien of the week but they arrived on the station instead of being "discovered" on some planet or ship in space. The series also broke several "Roddenberry" rules like making the series about war, and creating conflict between the main characters. This seems to have been a major inspiration for the latest Trek series, Star Trek: Discovery.
One thing that happens with DS9 more often than with the other series is that some people hate it for the exact same reasons that others love it.
We have a far more varied perspective on humanity thanks to our alien regulars Odo, Dax, Quark, Kira and Worf; as well as recurring characters like Garak, Weyoun, the Prophets.
The Prophets have evolved continually throughout the series. Sisko's mother, for example, started almost as distant and sibylline as the other prophets and then humanized herself progressively until she spoke to Sisko in a natural way. That betrays a certain lack of consistency.
Kira is the best character in all of Trek. I love the relationship between Bashir-O'Brien, how it grows slowly over time and becomes such a big part of their identities.
After spending twenty years in a virtual prison I wonder if O'Brien sometimes thinks to himself: "Maybe this isn't real either." There was a novel, I think it's by K. Dick where people would live five or six lives in a row, complete until death, (in only one night) because of some drug and then they would just sit there completely apathetic thinking that reality was just another one of these lifelong dreams.
I actually find she is one of my least favorite. Looking back, I would’ve rather had Michelle Forbes on the show.
I hate to pick on Nana Visitor but I'm forced to agree. I liked the Kira character but Nana Visitor has a limited range. Michelle Forbes would have been better.