Well, I tried ALE and it worked ok. Compared to the neovim built-in lsp client it just doesn't display as much info and does not support multiple hints per line. There's also CoC which should also work with regular vim and which I've used for a while, but it wasn't very stable for me (the auto-insertion of import statements made it crash frequently for example). The built-in lsp client seems to be the cleanest, fastest and most stable implementation. Using nvim-lspconfig it was fairly easy to set as well. It just took me a while to find out how to disable all the distracting live-/auto- completion, underlining, inline-hints etc. (vim.diagnostic.config)