what the bass is made out of, or who makes it?
~gR~

may be neither if you are a good player or both if you are looking for specific things in a bass.

how it fits you ;)

but to answer your question, i would say "who makes it"... because if " X " makes good quality bass, its already obvious that its going to be "made out of" good stuff, right?
(for example i can't imagine those very talented luthiers out here, using crap stuff)