As someone who loves both DS9 and B5 and is grateful we got both, I'm always glad to find another who doesn't play the one against the other game. Also, Quark is my favorite as well! (And I smuggled in a very small DS9/B5 crossover in my s6 of DS9 fic Quark's Day, plus I wrote a genuine "When Garak met Bester" type of crossover titled "Coming in from the Cold" (because I just had to).

Re: B5, I didn't write fix-its for Talia and Ivanova exactly, but one story about Lyta and Ivanova which includes a bit of hope for Talia at the end, and one story about Control (i.e. the alternate personality implanted in Talia) meeting Bester. But most of my B5 tales tend to feature Centauri or Narn, as these are where my B5 heart truly lies.