I thought all the Q episodes were great.
and I love how the OP says Q was featured "quite a bit"....sure if you call three episodes "quite a bit"
One way to look at that, is that to some it felt as if he was in more than he actually was, that isn't a good thing. Q appeared in 8 episodes of TNG, yet did it re.ally feel as if it was 8 episodes?
It could also be down to the fact that those episodes where his tenth, eleventh and twelth appearences which to some might have lent to a feeling that the character was overused.
For me Q' weakest appearance in VOY was in the"Q and the Grey", as others have already mentioned the best use was in "Death Wish"