The TV show? In that case the DVD set order is the canonical one and is plot/story order. That they were originally aired out of order back in 2003 was a one-off aberration due to studio leadership not understanding or being on board with what the show was about.

Let's call it "production order" then. Firefly was famously broadcast out of order.

I wouldn't call that a counterexample; if you watch Firefly in production order (not broadcast order; the broadcaster was moronic in reordering things), then you get the best experience.

I think it's more fair to call Firefly an edge case, instead.