It depends on the use, but I will go with paper.
Would you rather go to the Arctic or the Antarctic?
Antarctic. I hope to meet some tap-dancing penguins there.
Would you rather be a cop or robber (assuming no one dies, and you have equal chances of either arresting a crook, or getting away with the money)?
A cop. I’ve got a serious tendency to fighting injustice.
Would you rather be able to fly or breathe in the water?
Fly
Would you rather fight a mad bear or a mad skunk?
Mad skunk of course. I could kill the skunk but the bear will tear me limb from limb? Would you rather die right now or live until you’re 200 but you will have every kind of cancer?
- I mean, it’ll be painful with all the chemotherapies and such, but I still have a lot more things I want to do on this Earth!
Would you rather be a rat in a kitchen or a fish in a trawler net?
A rat in a kitchen. I think they always stand a chance.
Would you rather be attacked by a dog or a cat?
Depends what breed. But if it was say, a Doberman, and a Lynx, maybe I’d go for the feline (claws hurt less than teeth!). 
Would you rather drink a glass of one-week expired milk, or eat a slice of one-month mouldy bread?
I’d take the bread, b/c white milk makes me nauseous unless it’s in cereal. Would you rather die your hair purple or orange?
Orange. If it’s the right orange, I could pass it as real.
Would you rather be unusually tall or unusually short?
Unusually tall. I can tower over everyone, and I wouldn’t even have to jump to shoot the hoop in basketball.
Would you rather be Mr Obama or Ms (Julia) Gillard?
Gillard. I don’t want to deal with USA’s problems right now. Australia is much more pacific.
Would you rather be involved in a dog fight (a fight between airplanes) or in a naval fight?
Naval fight.
Lol, I just noticed this. Why are most of these violent, morbid, or just generally negative? Let’s lighten up, people! 
Would you rather have unlimited money, or fulfill all the things you want to do in life?
Fulfill all the things I want to do in life (which include having a nice amount of money, by the way 
)
Would you rather be made of paper or glass?
Paper. Much more flexible than glass, and there’s waterproof versions.
Would you rather have a baby monkey or an adult dolphin as a pet (Assuming you had an exotic animal license and it was for preservation purposes)?
I would rather have a dolphin, monkeys creep me out!
Would you rather be the sand castle or the wave?
The wave. Not sure why.
Would you rather be in an earthquake or a hurricane?
Earthquake. Hurricanes are too wet.
Would you rather be a great musician or a great athlete?
Musician. Oddly enough, that was one of my first questions
Would you rather read Harry Potter or Twilight?
Harry Potter. Twilight is for horny, pathetic girls with no life. Would you rather be Mr. Incredible or Buzz Lightyear?