Cyanogenmod nightlies are now available for Samsung Galaxy S5 Sprint Model. You are finally free from the limitations of TouchWiz (if you want to, of course) as the first nightly build from CyanogenMod is finally online.
In order to flash the new ROM you will have to unlock your bootloader, of course, and you have to keep in mind it may be a bit buggy. In the future a new and stable version will be available of course, just in case you don’t want to risk it yet. Other Galaxy S5 variants are being worked on, as CyanogenMod announced on their Google + page.