The Samsung Galaxy S5 is scheduled to get Marshmallow eventually, but some models only received Android 5.1.1 in October, meaning most customers are in for quite the wait. Even when the changes do arrive, they may ultimately taste quite a bit like TouchWiz, and that's not a flavor everyone likes having on their tongue.
Fortunately the good old standby option, flashing a custom ROM, is still around, reminding us of the perks of Android's open source foundation. CyanogenMod nightlies running Android 6.0 have made their way to the Galaxy S5, codenamed klte. The full download comes in at 286MB, not counting the GApps package you will probably want to grab as well.
Now for the caveats. These are nightlies, so they may not provide the most stable experience. Whether that bothers you or not, you will need a GSM model to dive in right away. That said, this is not intended for AT&T carrier versions, nor is it going to work for Sprint (kltespr), Verizon (kltevzw), or US Cellular (klteusc) devices. Hopefully they will get the goods at some point, but considering only the Sprint model received CyanogenMod 12.1, maybe not.
- CyanogenMod Downloads