Theatre, because that's what I'm trained in and where I want to be. However I do have subtle moments in my acting that can't really be seen onstage, but is picked up on film.
My features are all very pronounced, so my expressions are often large and good for theatre, where, if my face were on a 20 foot movie screen, it would probably frighten most movie-goers.
I've been trained/am training in acting for the stage. But I honestly think that if I would ever "make it" it would be in film, not the stage. I've been told that I need to be "bigger" onstage but it just feels a bit unnatural to me. I'm much more subtle than a stage actor should be which is a shame because I love the theatre but I also would love to do film too. Ideally I want to do both well! haha