For me, it was a tedious, already well worn trope ran into the ground. There are some great episodes that occurred under that arc, It's Only A Paper Moon for one, but I still generally avoid the Dominion War episodes.
How can it be a 'trope for Trek when Trek had never done such a thing before? Individual battles yes. Come right up to the edge of but avert at the last minute yes.
Full out, "it's either us or them warfare"? No. That was new.
And it was a fascinating joyride as "perfect people" were forced to confront head on a decidedly imperfect universe.
They came darn close to doing exactly what Admiral Ramirez fears in his address to the Federation in Axanar: "destroying the dream..." You could probably make the case that they did, given Sisko's action in "In the Pale Moonlight" or just about anything Section 31 got up to.
The war stories may not have been a trope for "Star Trek" in particular, but DS9 certainly relied on a lot of those war genre tropes to tell their stories.
"In the Pale Moonlight" aside, most of the stories felt lifted from old WWII movies. That just didn't work for me. In the end, I didn't think DS9 had any unique perspective on war, anything meaningful to say about it or how it really affects the Federation or the characters.
Other than Nog, I really don't see what anyone really lost in the Dominion War, how it changed them.
While not anywhere close to perfect, at least "Babylon 5" was trying to say something about the responsibilities and consequences of war, particularly in the arc of Londo and G'Kar.
But that's me. YMMV.