I'm about 6 episodes into a DS9 rewatch. It's been about 5 years since I finished my last complete watch through of DS9. I agree with the OP that DS9 puts DSC to shame. But I have one big question. Season 1 has several episodes already with aliens from the other side of the wormhole. I don't remember if this was addressed later when the Dominion conflict came. Did the Dominion conquer all these worlds? Or did the writers simply forget them?
They seemed to be minor powers. The Dominion might have tolerated them. The Dominion didn't extend to the wormhole until around season four during the build up toward the war iirc. Also, some of them may be from regions well away from Dominion space.