Imo the best way to nerf quest rogue is to make the quest more of a buff instead of an aura. This would limit how much power quest rogue could bring since buffs wouldn't be copied by cards like zola, sonya, or bounce effects. Namely I would make it say something along the lines of "Give all your minions on the battlefield, in your hand, and in your deck +4/+4". The deck would still have the power of playing cheap giant minions but with that change alot of what makes quest rogue unfair isn't there anymore since you can't bounce the minions anymore (at least if you want them to be big).
On a side note even though quest rogue isn't top tier it's still a problem deck due to how polarized the deck is in its matchups. A deck shouldn't have 20/80 and 80/20 matchups because it turns hearthstone games into a coin flip because the deck either loses or wins depending on what it queue'd into and not based on more skill testing factors. In fact several decks are like this currently with the other big culprit being odd warrior who also is very polarized in it's matchup spread.