There are already rumors of a Galaxy S7 flying around and we are only a few months into the release of the Galaxy S6. We still don't have Cyanogen Mod for the device. We don't even have an unofficial build. With no CM build there are zero AOSP rom options for this device. Every rom is based on Touchwiz. This would be ok if we had locked bootloaders, but it is pretty frustrating for a device like the T-Mo S6 which ships with an unlocked bootloader.
The CyanogeMod team had officially stated that they would not support devices with an Exynos processor like that of the S6. While there is hope that we may one day see CM on the device it doesn't seem likely that it will happen any time soon. If you still want some control over the themeing and customization of your phone you might want to try out the OZOP rom. OZOP stands for One Zip One Place. They are focused on providing you with an optimized Android experience while also packaging pretty much any customization option you could want or need. The rom is based on 5.1.1. The themeing options here give you a deep custom look just like what you would get from a CM theme. Head to the link below for the download and install instructions.
via XDA