Best = In the Pale Moonlight.
You know, I never thought of this one as a bottle show, but I guess it -could- vaguely qualifty. Though they brought in a lot of guest stars and designed a new Romulan shuttle just for Vreenak.
Duet still sets the high water mark for what a bottle show should be for me though. That was the crowning moment of season 1 and really not only told a powerful story but set the theme for DS9 as a whole.
The worst? ANIS takes the cake for me. Bad writing, bad acting = bad episode. Go figure.