I first saw DS9 around 1998, back in grade school. I had always been a Trek fan, my dad being a TOS fan, while I had also enjoyed TNG. A friend of mine, who was a huge TNG fan and was trying to get me to play the Trek card game with him, showed me Improbable Cause/The Die is Cast. It really spoke to my sensibilities, even back then, of themes and structure (the episodes connecting more as opposed to being stand alones like TNG or TOS).
I started watching reruns the next year on some obscure channel, around the time they were showing In Purgatory's Shadow/By Inferno's Light and was HOOKED. When the DVDS came out I bought them immediately and caught up with the show, while still seeing it sometimes on Spike. I then proceeded to get my cousin and my brother into, and later my dad, and even later my fiancee, all of whom consider it one of their favorite shows, especially my cousin and fiancee.
It remains not only my favorite Trek, but my favorite TV show to this day. Thanks to everyone involved with the show and Happy Birthday to DS9!