I think the comments Dan and Kyle made about DS9 are thought provoking. I personally think that DS9 was the best series. Dan apparently thought it was so bad he couldn't get through the pilot (though the pilot for every trek series was terrible, so that isn't really a fair measure of quality.)
Dan says that he watches Star Trek for escapism, and from that perspective I can agree with him. DS9 focuses more on main cast character interaction (internal conflict) while TNG is mostly about the fantastic adventures of people in space (external conflict.) Different approaches to Star Trek both with their strengths and weaknesses.
Also, I want to point something out that everyone, even Dan, seems to think but is wrong. Sisko started no war. Not the Dominion war, not the Klingon war, none of the wars in DS9 were started or even the fault of Sisko (except in that he discovered the worm hole, the focus of all these wars.) What most people seem to think was Sisko starting a war was actually Sisko refusing to respond with appeasement when a fascist government took over a neighboring nation though force of arms.
Kyle made a point about Sisko shifting his morality to suit the situation, and that serving under such an officer would be intolerable. I disagree. I think that Sisko did not hold to the standard Starfleet morality but remained consistent within the moral code that he followed. Sisko believes that the ends can justify the means, especially when billions of lives and the freedom of an entire quarter of a galaxy is at stake. Sisko did not hold a specific set of rules he would never break under any circumstances, but he did carefully judged each situation before resorting to means outside of normal morality.
Picard, on the other hand, I might find intolerable to server under for moral reasons. On two separate occasions, Picard was willing to allow an entire sentient species be wiped out by natural disasters when it was within his power to easily save them simply because the prime directive prevented them from interfering. In "Pen Pals" (TNG S2E15) a sentient race is about to be wiped out by a geological instability the Enterprise can easily fix without the race even knowing they were ever there.
The dilemma is simple: Do we save these people, or allow them to be wiped out because the prime directive applies in this situation. The fact that Picard or anyone else would even have to think about this before fixing the problem is, to me, disgusting and morally reprehensible. Picard decides that the prime directive applies and that he will leave these people to their fate. Data is only able to change Picards mind by playing a message from a small child of the species. Only when he actually hears the plea for help of a suffering child is he finally willing to bend his moral code so he can save an entire planet full of people.
And do you know what the real kicker is? This episode takes place in season two of TNG. If you didn't know, season one and two of TNG had many episodes that were essentially Picard telling anyone who would listen how morally superior the human race is.
What do I take from this? Picard is morally inflexible. He has accepted a rigid set of moral rules in place of actual moral consideration. Picard is willing to commit negligent genocide because he has allowed himself to be duped into believing it is actually the moral thing to do! I would find serving under such a man intolerable.