Blu-Ray, but it's going to be tricky.
I have a Blu-Ray player and a small-screen TV. My family has a DVD player and a large-screen TV. My brother and I are going to want to watch it and probably invite some friends over. We should see it on the large-screen TV, so what I'll end up doing is taking the Blu-Ray player with me, unless we both purchase the movie.
OTOH, I don't know if my brother will purchase the movie, he's more into the Prime Timeline and the novels.