TNG will always be a sentimental favorite, but objectively speaking I don't think there's any doubt that DS9 was the best-written show. By far.
I'll have to disagree with that. Consistency-wise, I think TNG S3-S6 was the best period for Trek writing. I can definitely see having DS9's writing as your personal preference, and it definitely aged better. But, DS9 did fall back on 'TV standard scenario' quite a bit, and although its main villains were compelling, its minor villains were your standard 'I'm going to be nasty for no reason' villains. You know 'Scott the Dick' from South Park? That was pretty much every villain in the series who was not Dukat, Winn, Weyoun, a Founder, or a Jem'Hadar first. (Either that or they were random psychopaths murdering people cause crazy and stuff)
And, again not counting seasons 1-2, TNG didn't have those 'flat out facepalm' episodes like Sword of Kahless where generally rational characters were acting like maniacs for no reason.
I can see not liking TNG's idealism and preferring DS9 more, but from a pure 'Making me interested in the drama without falling back on contrived personal drama' standpoint, I have to pick TNG's writing from seasons 3-6 over DS9.