Have you watched Makar play? He's not that great defensively. QH is, IMHO, at least as effective defensively as Makar and I'd argue he's moreso.
As far pure defensive abilities, that's not Miro Heiskanen either. He's more of a great all-round dman with excellent mobility and goalscoring ability.
I mean, all three of Makar, Heiskanen and Hughes are elite because of their all-around play.
None of them are tops in the league in terms of pure defense.
I would have them as such (not just this season, but taking into account body of work as well):
Heiskanen - Very good defensively
Makar - Good defensively
Hughes - Average defensively
For this reason, even if I thought Hughes was on par with Makar offensively (which I do not think, although the gap is quite small now), I would still have Makar ahead.
Heiskanen is a much closer battle, given that Hughes is clearly superior offensively, while Heiskanen is clearly superior defensively. I think it's a coin flip between them.
I do not think Hughes is on the level of Makar or Heiskanen on the defensive end, however the advantage they had over him at one point has narrowed. I do think he has more room to grow in that area however.
On the offensive end, I think he's clearly above Heiskanen now (remember, Heiskanen finished 3 points behind Hughes last season and also has a 26-point playoff run to his name), and still slightly behind Makar, but adding a shot to his arsenal has made it very close.
Hughes is leading the league in scoring, but Makar is only 3 points behind him with 2 games in hand.
Anyway, none of this is meant to dump on Quinn, he's taken a big step forward this season in all areas of the game and it's extremely fun to watch. I was resigned to the idea that he would top out as a top 10 defenceman in the league but he's smashed right through that and solidified himself a spot in the top 5. I would love to see him win the Norris this season.
I just try to look at things objectively and based on what I've seen, I think he has room to grow on the defensive end.