Which insulation to use in new construction?

Hello dear forum members,

our new building is imminent. Now I can choose between an insulation between rafters as full rafter insulation (glass wool) and a blown-in insulation made of cellulose. The offer for the insulation between rafters is generally higher.

How would you insulate your attic if you could choose between the options mentioned above?
I thank you in advance for your input!
Best regards
Matthias

Between rafters. Then I at least know that there is something everywhere.

We have blown-in insulation. It is certified and must be done by a professional company. We did not want an ETICS with plastic... we only have cellulose insulation and wood fiber boards.

If executed professionally, the two alternatives are equally effective.