DS9 is very much my favourite of the Star Trek
series, so I'm definitely glad to have a forum and to hear other fans' thoughts on the series.
I also enjoyed DS9's treatment of religion; it struck me that at some points (particularly in Sisko's and Kira's cases) the series had an almost existentialist (Kierkegaard, not necessarily Nietzsche) bent to it. Also some of the strongest, most three-dimensional characterisation in any form of Trek
, IMHO: Kira, O'Brien and Worf in particular.
As to how many times I've seen each series? TOS: all episodes once; most of them twice or three times. TNG: whichever episodes my parents had on VHS five times each at least; some I haven't seen at all. DS9: all episodes at least three times. VOY: haven't seen yet, except for 'Unimatrix Zero'. ENT: all episodes once (that was enough).
Good to meet y'inz!