I say get both
. But hey, if it's only the choice of one it'd be tough for me to chose too. I agree with everyone else... a bullsnake is an awesome snake and they sure have neat personalities compared to what you're used to.
If you are actually planning on breeding something I think live-bearers are easier just because you don't have to worry about incubating eggs. I'm going to hopefully breed my BCI's next year at some point when the female gets bigger. She's going through an awesome growth spurt right now, and sheds almost every 2 weeks. But if you find a love for bullsnakes then good luck to you!! I can't wait to see it when you get it