Personally, except for "Death Wish" which was outstanding, Q started going down hill with Voyager. In TNG, Q was fresh, fun and funny. And Q had a valid story arc in TNG starting in Encounter at Farpoint and ending with All Good Things. In Voyager, there was no story arc, so Q felt completely shoe horned in for no reason but to milk a popular TNG character. And, John de Lancie was starting to show some age and the humor was getting repetitive. Plus they tried to repeat the chemistry between Picard and Q with Janeway and did not quite work! Then, we get ridiculous eps like Q2 with a teenager Q and it was over!