I'm in the hands of a smart, solid narrator, who's in the driver's seat, taking me on a journey planned with conviction. Action that keeps the script moving, keeps it tight, urgent. A script in which subtext and mood have been clearly cultivated so I really feel the material, feel taken on an emotional, visceral experience. That and more turns me on. The major turn offs are scripts that read as if little or no ground work has been done.
Most writers love to write and hate to prepare.
Generally, writers who prepare deeply write better scripts. Major turn ons are scripts that feel well thought out, economically written and executed with the obvious realization that every scene needs its own agency and magic. Keep reminding yourself that even though you are writing, what you are really doing is creating a visual experience. Cinema is a visual medium that happens to use language as one tool toward its imagistic end. The need for instant gratification is a writers quagmire.