Mine would be the first Warren Zevon LP, "Warren Zevon". His debut album is wonderful.
This is, indeed, a great record--one of my favs--but it's not actually his first. That would be Wanted Dead or Alive from 1969, re-released on Pickwick in 1979, which is when I found it. A bit rough in places, but one can readily hear the artist he would become.