I love netboot.xyz. I use it all the time when setting up VPS systems. A lot of KVM-based VPSes have iPXE as a boot option so you can chainload directly into netboot without having to use an ISO.
I prefer installing the OS myself over using any images provided by the provider, so that I know exactly how it was set up.
Netboot.xyz has tools to build your own custom version of it too, with your own options. Useful if you want to host it on an internal server. It's essentially just a set of iPXE scripts.