I think a case can be made that Morrissey has been slightly better the last couple of years.
I’d rate them similarly - clearly in the top tier superstar defenders with Makar, Quinn, Werenski, Dahlin and Fox (yes, I’m giving Fox a bit of a pass this year for that dumpster fire team).
I think form, I’d go Morrissey and body of work I’d go Heiskinen. Voted Morrissey to make the poll a bit closer but thrilled with either anchoring my Cup contending defense.