One of my favorite AOSP roms for Nexus devices ever is the Clean Rom series by ScottsRoms. The Clean Rom brings you stock vanilla AOSP Android with performance tweaks which improve the overall user experience. I have also had better battery life with Clean Rom builds. The latest version of Clean Rom brings this build up to 5.5 and is based on Android 5.1 LMY47O.
This Rom also uses the Aroma installer which means you are able to make this rom your very own choosing which AOSP, and extra apps you wish to include or omit. You can chose between the stock or nova launcher. Some misc apps that you can choose in the aroma installer include ES File Explorer, Ad Away, Reboot Manager, AOSP Gallery, and AOSP Music. There is a native reboot menu built in which will allow you to power off your device, or reboot into normal reboot/ recovery reboot/ bootloader reboot.
The main changes in the latest update to 5.5 include a complete rebuild to 5.1, addition of Native power menu, and the removal of the reboot app. Head to the source link below for the download link.
via ScottsRoms