The godot language server also seems really nice. You just add something like: lspconfig.gdscript.setup({}) to your init.lua (or equivalent in init.vim), then it works with the normal neovim autocomplete. More significantly, it means you can get the really great godot docs in a floaty window bubble without any context-switching.
How much worse is support for c# than for GDScript? We want to move away from unity and the whole team is already fluent in c#.
You can use both languages in one project, so I'd recommend trying GDScript at first. It's a very simple language so it can be picked up quickly, but as soon as you feel yourself reaching for LINQ or wanting a proper type system then switch that script to C#.