TNG was the far better show than Voyager, but that had most to do with two things: Patrick Stewart, and the writing of individual episodes. Otherwise I think the intellectually progressive nature of the show is what makes it stand out as 'special'. TNG was something special and unique, Voyager was just a pretty good spaceship show.
Voyager, however, has the better secondary cast. TNG's Roddenberry box was a double-edged blade. On one hand, Starfleet officers should seem like consumate professionals, not catty drama queens. On the other hand, it would have benefited from characters to counterbalance Picard and Worf's stiff introversion that weren't just exaggerated female stereotypes. Voyager's cast had so much untapped potential. Chakotay conformed immediately, Kim never did anything but shut up and do his duty. B'elana's rough edges never showed through after the eighth episode or so, Paris's showed up for one episode here and there then went away. But even the neglected characters got me more invested than characters like Troi or Laforge.
If Voyager stuck to its premise it could have been something more special, but it decided in the end just to try to be TNG only without the commitment of message.
I would disagree and say DSN had the best secondary cast for the most part, Dukat, Damar, Weyoun, Garak to name just a few. As for it's primary cast most of them got developed well, had episodes focused on them. True some more than others.