Scripts are easier to get in front of people (though they might only read the first ten pages) BUT you need to be in LA to make, shake and close the deal.
Novels are harder to write, require more time, and when you're done, if you've never been published, it's hard to get taken seriously or even read.
Graphic Novels are nigh impossible, because the industry active closes out newbies AND you need to be super-talented to do everything OR you also need to hire a penciler, inker, colorist (though you cna go black and white) and a letterer.
It's a Quixotic challenge whichever route you go. When I work a comic book project, I am usually thinking of the movie adaption (if only very loosely) and then there is always the novelization. Write a great comercial novel and you'll see a movie version. And scripts usually get at least a novel tie-in.
I would say that a script is easier of the three. However, if you want this baby to see the light of day, I would consider getting some published credits through short stories and then you stand a better chance of landing the book deal. Or write some comic books for indie publishers (and make contacts with the art people) THEN do the graphic novel. Or, write some short screenplays for students and indie directors, get some credits and contacts THEN push your baby. But that ISN'T the easy way.