If you like to spend some time on customising, use Dirty Unicorns.
If you want something stable but not Stock use Pure Nexus with Elemental X kernel.
Nexus devices have always been, in my opinion, until the release of Nexus 6, the best Value for money option. What I like the most is that they are pure Android without any Samsung or LG apps. Having a Nexus is like a responsibility to “play” with it. And what I mean by playing is actually customising. Starting from a simple Launcher and some Themes to custom ROMs and Kernels.