Which to get - iPhone 5C or 5S?

I currently have an iPhone 4, which I've had for a little over 2 years. I'm probably going to upgrade soon, and was wondering which iPhone seems to be a better option.

The 5C is cheaper, but the looks of it maybe aren't as impressive as the 5S. I don't really know if that's worth an additional $100 though.

I'm a soon-to-be 18 year old guy, if that changes anything, so what color on a 5C would you recommend if I got it? And in general, which iPhone would you recommend?

All feedback is appreciated, thanks.

IF YOU DON't CARE ABOUT THE FIRGERPRINT SOFWARE and the 5c being a plastic finish, then get the 5C

The 5C definitely seems more lighthearted while the 5S looks more. Maybe professional? If you plan on getting a case which is basically necessary for a fragile iphone, then I think getting the 5C is a good choice as the phones can't be very different except for the 5S fingerprint thingy. Color wise, white or maybe yellow(?) would be nice.