I am planning a cabin with ICF walls, a shed roof, big eves and metal roof. The spans won't be great so the trusses do not need to be tall, we may use I-joists. I would like to avoid a "hot roof". What are the best ways to insulate?

Cellulose or blown fiberglass

Is the cabin going to be heated all the time, or only during intermittent use at a low duty cycle?

What US climate zone?

Sometimes going deeper in on the ceiling/floor trusses to allow deeper insulation can be cheaper/easier than building out an "energy heel" for the rafters. If it's a cathedralized ceiling rafter truss, not a floor truss that may be the best option, using the flanges of the truss to support the exterior side ventilation gap air barrier, and filling it full of fluff.