I have lots of thoughts about this but I won't bore
the group with all of them, at least not now.
Conventional construction. Perhaps poured concrete
floor, concrete block wall, truss roof. To be easy
that would require concrete from reddy mix, and
trusses that come from the factory.
Offhand straw bale wouldn't seem to be that labor
intensive. Sort of like building a brick wall with
only a tenth of the number of bricks. Or is this due
to the need to stucco inside and out?
A structure built like a pole barn might be the simple
construction though finishing it might offset the
simple construction.