https://vanilla-servers.org/They plan on using the Nostalrius core when its released. They have a beta server going now, no cash shops or pay 2 win nonsense. GMs are active and are requesting bug reports, which are few and far between. The server that is running now is "beta", to allow you to level up now in the meantime until Nostalrius core... with plans to let you transfer to the new Nostalrius core server once its released.
I'm very happy with their work so far.