Their story arcs were known from the outset. Each (main) character has their own hero's journey and side quests. Both had satisfying endings.
Also, officially, Capt Sisko is the GOAT. With Capt Janeway placing a strong 2nd. Though Capt Pike (Strange New Worlds) is quite promising, but only time will tell.
Whereas Voyager has most of my most favorite episodes, esp wrt Ensign Kim, DS9's characters are legend, esp Quark. I couldn't pick a favorite DS9 character (or story), even on pain of death, because I cherish them all equally.
And yes, this is the same Dominion War that was referenced in the last season of the Picard series.
OTOH, DS9 is the only Star Trek that my wife will willingly watch with me; she finds the others too campy. As another data-point she likes the dominion war arc as much or more than B5, which was her favorite sci-fi series previously.
I might also be slightly biased in favor of cardassian plots and actors, if only for Stewart's acting in Chain of Command.
The dominion and bjoran plots didn't really resonate with me at all, unfortunately.
Even saying that though, I don’t think you can say one is better than the other. I can see why your wife likes them both though.