According to BZ :
Rick Blaine wrote:

Have you considered blown fiberglass or damp cellulose?

Right now there are no walls, just bare studs, so I've been thinking of
some kind of lay-in insulation before having a drywall contractor come out.

How warm do you want it to be? About the cheapest, but still pretty
good, you could install 15" unfaced batts, and line the inside with
vapor barrier. That's better than Kraft faced batts. You'll
lose a small amount of R having to compress the batts slightly, but the
loss would be minimal.

Rockwool batts will give you a slight improvement in R, as well as
better sound deadening, and is easier to work with. Normally costs
the same as fiberglass.

Blow-in is likely to be more expensive, because you have to get the
walls up first, and then patch the injection holes, and you may
have problems with vapor barrier. If you were to go with blow-in,
I highly recommend blow-in rockwool over cellulose. Won't pack
even when wet.

There are forms of sprayed cellulose that might work without
having to put up the interior walls first, but, a foam would
be a lot nicer, (as well as a lot more expensive).
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.