I recently came up with two different ideas for a novel, and am having a hard time deciding which to do first.

The First:
Robots became sentient and wiped out humans long ago. Now a robot scientist has determine how to create a human from genetic material he found. Robots are divided. Some are excited about the return of the humans while others fear they will not follow the robot society and overthrow their creators.

The Second:
There once was a tribe who was revered by all and became famous. Throughout the years,they disappeared. Some said they had been assimilated, others said killed off, and still some believe they are in hiding. Now, a group has arisen claiming to be their closest descendants and the true bearers of their heritage. They become genocidal and authoritarian, using their supposed heritage to justify oppression and murder of other groups. Eventually, they run into the actual original tribe, but the tribe looks nothing like them, so they treat them like all the others and attempt to kill or oppress them.

the first: you'd have to be careful on how you do that. There is actually a science fiction short (done my Issac Asimov I think) that's pretty much about that. Wish I remembered the title so you could read it. Not saying you shouldn't do it, but it's knowing what's out there so you can do your own thing.

the second: sounds interesting, but you should be aware of the heavy tones of slavery in it (if you didn't know that already). So you'll probably have to do your research so you get the feeling of oppression down since opressors do more than wave their guns about. And genocide is one of those things that unless you do a lot of studying up on, it could come across wrong and unbelievable.

Ultimately the choice is yours, but with both you need to do your research. With the second though, I will be honest, you're going to have to be careful and very mindful with how you approach it, given all the overtones.

im a bit skeptical about the second idea but the first seems doable although maybe you could change it just a bit.
maybe instead of robots they can be some kind of animal or vampire?
(you can never go wrong with vampires)
i like the idea and would like to read it if you write it!:3

I don't think the idea should be changed from the original just to satisfy the current popular trends; a writer should be able to pick what they want to do, and go with it. Personally I think a vampire making a human would be retarded; and I happen to like vampire novels, and vampires of all kinds (even the sparkly ones), so I'm not saying that out of some vampire hatred.

I mean, how would they keep from feeding off the human they made?

As for animals, I don't know, it could be possibly interesting though I know a lot of people who would pass on it just because of it being animals. Then again, the same could be said for robots.

I prefer the robot idea, personally; making sure that the idea is uniquely your own and takes many different directions so that you can't get in trouble with anyone else saying you copied them (though a general idea, I believe, cannot be copyrighted unless it is identical. Otherwise, we'd have nothing to read that was current D:)

The second idea to me sounds a little interesting, but not as much. I'm sure there would be loads of ways to take it to make it more interesting, but to me it just sounds like an interesting twist to genocidal stories which I don't typically read myself. This, all in all, is a matter of preference.