When they ditched the whole “peace and understanding” thing and started battling the Borg, I thought TNG got very good.
That was due to the addition of fellow UNC-Chapel Hill alumnus Michael Pillar to the writing staff. He created the Borg storyline and the focus on action that saved ST:TNG. It's not too much of an overstatement to say that Pillar saved the Star Trek franchise at a critical time when it was languishing.