I've tried a lot of multiple file, find and replace solutions, and spectre is the one that seems to make the most sense to me. There's not much to it but it's very effective. Regex works the way that I expect and it's easy to toggle options on and off.
I have just installed it and it looks really neat, i usually switch back and forth between neovim and emacs (depending of the type of project), and use deadgrep and deadgrep-edit-mode for that but may as well use sometime nvim-spectre..
https://github.com/nvim-pack/nvim-spectre