TNG gets a lot of flak simply because it was done in episodic format.
I think at the time, that format was fine. Could TNG have benefitted from an ongoing arc? Definitely! We might have missed out on some stellar episodes though because of it.
Most of DS9 once the war kicks in is war war war, and personally I don't even think that well done (I am rewatching it a second time right now, and I am enjoying it more than the first time, so I may change my mind on a few things).
I just finished S2 of DS9, and while it's been decent so far, no way does it compare to TNG's later seasons. We'll see how S3 holds out.