Mark Benvenuto gave the following description:
I have tried both ccls and clangd. They are both good but different. ccls offers better code lens (inline hints like 6 refs above a function), better global index lookup, and things like inheritance hierarchy. clangd works out of the box, works on Windows easily, and the typing completion works better. I have used clangd only a little bit in the past few weeks. In your repo, echo .clangd .git/info/exclude this allows you to customize a local .gitignore.
We should consider which is the best option. It seems VS Code intellisense does not perform as well as either ccls or clangd.