jUsT bE YouRseLf BrO!
There's a difference between what game you want to make, and the game you are best suited to make given your skillset. So, if you're making this poll to decide which artist to hire, that's absolutely fine. But if you're already good at making art yourself, absolutely stick to what you know best and continue getting better at it, even if that's not exactly what you want. Where the mantra "make what you WANT" makes sense is story/fetish selection. Do that. It won't you do much good to work on something that you don't like, or even worse, actively repulses you.
1) If you're indeed asking what art to comission the answer is 2D. 2D all the way, not because 3D is inherently bad, but because most 3D is some uncanny shit, that actively makes the game worse for some people. No art is genuinely better than dazshit. Seriously, Illusion HS is better than that.
2) Something like 3/4 story + gameplay, 1/4 art. Good art is nice, but it won't make a game on itself. As long as the art isn't actively driving me away (see: uncanny daz shit) I don't really care if art is less than perfect.
3) That's kinda a false dichotomy. A game with ending can be perfectly replayable, as long as it has gameplay.
4) See above, do what you like most.
5) This question I reeeeeally don't like. Look, you're confusing two things. Setting and character realism. People like realistic caracters and generally don't give a shit about the setting in porn. I'm gonna vote fantasy on this one, not because I like the setting per se, but because it gives me an extra early indication whether the author is any good. With bad fantasy it often becomes much clearer from the beginning so I don't have to waste time.