Well, hmmmm....
I grew up on TNG and watched TOS over and over too. DS9 was excellent, and I think probably the most realistic depiction of the Trek universe (grey vs. B/W). TNG did some grey world work too though. I can't really stand most of Voyager, torch bearer of Deus Ex Trekkie Machina. Enterprise was decent, but yeah some of it is very weak. It has its redeeming qualities though.
Overall, I kinda go by the feel of the show and how much I liked the actors/characters. I think DS9 and TNG had by far the best cast. No contest, really. I'm having a really tough time deciding which I would think best though. I'd vote for both TNG and DS9 if I could. Each has flaws so it's hard to go with one over the other.
I suppose though that I'd have to go with TNG. That show is like an integral part of me.