Well, if you're asking in generic fashion...
Characters: I just loved TNG's overall cast the best. The only problem with them is they were rather cliquish and didn't interact with outsiders all too often or have drama among themselves. If we're counting secondary characters and guest stars DS9 runs away with it.
Story: No contest, DS9 is the only Trek series that actually had an overall direction to it's story and multiple subplots that all tied together.
Special Effects: I gotta give that one to Voyager. They did pull off some remarkable effects and cool shots.
Overall package? Easily DS9. There was drama, a compelling story and while the effects are there to enhance the story, they didn't slouch in that department either.