Speedygi
Moderator
my girlfriend owns a 5S and that battery life is suprisingly underwhelming. It might not be representative (having said that we went to an Apple Store and got it scrutinised, apparently the battery is fine) but her phone hardly makes 5-6hours active usage. And that's with many features switched off. So in my experience the 5S battery can't keep up with the C but that's just two of billions of devices compared, don't know how they stack up in general.
I maintain the opinion that the 5c only slightly edges out the 5s for battery life. The 5s on the days I use them rarely needs a charge until the end of the day, just like the 5c, but maybe the 5c just has like a half-hour advantage at the end of the day. To me, that says that the whole comparison really is nothing incredibly lop-sided and it shouldn't be blown out of proportion. But that's my opinion, take it however you will.