What do you define as a "filler" episode? Some of DS9's finest moments were standalone stories, and often they were money-saving shows too.
Alright, a couple of episodes I consider to be filler, and not particularly good filler:
Looking for par'Mach in All the Wrong Places
Doctor Bashir, I Presume?
A Simple Investigation
I haven't finished the season yet so I'm sure there's more.