DS9 really came into focus for me and became my favorite show from S4 onwards. That's largely due to all the things that happened in that season and from that point on but also due to the music which, it seemed to me, was given a little more freedom. The score for "The Visitor" is particularly noticeable and powerful and came as a really pleasant surprise. But they also had somewhat more dramatic and suspenseful music used to build momentous events such as in The Way of the Warrior IIRC.
Later on, they built on that e.g. for episodes such as Call to Arms which had something like a Dominion or bad guy theme which was pretty cool. It gave all the events a lot more gravitas, I think, and the whole show a more epic feel.
Individual episodes that stood out to me (that I remember now) for their music include the following:
- The Visitor
- The Quickening
- Nor the Battle to the Strong (not quite sure about this one)
- In Purgatory's Shadow / By Inferno's Light
- Call to Arms
- Parts of the season six opening stretch (don't remember individual eps anymore)
- Far Beyond the Stars (though that's an exception anyway)
- In the Pale Moonlight
- Image in the Sand / Shadows and Symbols
- The Siege of AR-558
- Parts of the Final Chapter (again, I don't remember individual eps)
I thought David Bell was well as Paul Baillargeon. contributed some great music and were quite recognizable in their scores. I was never too fond of Chattaway's work, mind you.
Having said all that, I still think DS9 could have done so much more in terms of the music. For me, personally, music is very often the element that elevates a movie or a TV show beyond 'just' being great. My favorite movies, for example, all include a score that I really noticed when watching (e.g. Blade Runner, 2001, Donnie Darko, A Scanner Darkly).
nuBSG is my favorite TV show right now, and it has what I'd consider an excellent, exceptional score. It wouldn't be quite as special without it, and I don't know of any other TV show with music as remarkable as this. I agree that B5 had some great music but it's not really close IMHO plus, as someone else said, it's somewhat too synthetic for my liking.
It's interesting to see the DS9 scenes with the nuBSG music. However, I think DS9 would need music of its own to really fit (ok, that's no big surprise).
The first three seasons in particular would have benefitted enourmously from better music that was allowed to be an integral part of the show, I think.