Without a doubt, probably the best custom ROM to run on your Galaxy S5 is Resurrection Remix ROM.
Based on latest Android 6.0.1, Resurrection Remix ROM brings your Galaxy S5 up to speed with excellent performance, battery life, and a slew of great tweaks.
Antutu scores on Android 6.0.1 with Galaxy S5 and Resurrection Remix ROM scores 58,133! Latest version also brings even more performance improvements over previous Marshmallow RR!
While many of you still may be on TouchWiz, if you are not running AOSP ROM like Resurrection Remix ROM, you are missing out on all of the new Android 6.0.1 features such as DOZE mode, ability to convert your microSD into internal storage, app permissions, and much much more.
Not only will you benefit from latest Android Marshmallow, you will also get cool customization not offered by stock firmware like status bar customization, navigation bar tweaking, crazy navigation shortcuts like Gesture Anywhere, and even multi-window/floating multi-window.
Also, fingerprint sensor works so you can now fully enjoy both AOSP and your fingerprint sensor to keep your phone as secure as possible. With Marshmallow app permissions, you will also be able to get higher security as apps will need your “permission” to access your phone’s peripherals such as the camera, GPS, etc..etc…