Should I get a 32G 5c or 5s?

Should I get an iPhone 5C for FREE, or a 5S for $100?
(My phone carrier is providing $199)

I currently have a 4S. What do you think?

I wouldn't upgrade yet until apple stops updating the 4s, but I would choose the 5s because the 5c is lower quality than the 4s and it would be more of a downgrade.

I would say get none since there's no significant improvement BUT if you really want to do it, then get the 5S. Much better compared to 5C.

If your contract is up, then I would upgrade to a newer version by trading it in. They now take trade-ins and you can get a new contract, so it may be just like getting a free upgrade. At least you get something back for it and its easier then selling it on your own.