Sci-Fi. I think this would be the easiest for your creative process. The other two would require you to use things that already exist and you could face more criticism for inaccuracies.
Plus, I just like the Sci-Fi genre more.

I've already seen most of what the modern/past era has to offer in games and in real life. I would rather see something that I have never seen before.
My green thumb grew the tree my Trojan War horse was crafted from. With roses in our pockets we rally round the tombstones. Ashes to ashes, we all fall down.