[mark_l_watson]

I have no idea why you were downvoted for your questions. Weird. I will try to answer your questions:

One killer application of Vim and Emacs is development on powerful remote servers, for example, you might want 16 cores, a powerful GPU, and 64gig memory for a task so remote exploration and development makes sense. (VSCode does have a remote mode but I haven’t tried it.)

I have been using Emacs for 20+ years with Lisp. I just use Vim for quick edits to I can’t speak to using Lisp dev Vim support.

For local development on my laptop, I now use Emacs or VSCode about equal amounts for Common Lisp, Racket, and Haskell depending on what I am doing. Both are fantastic dev environments.

EDIT: Slime may be old, but it is tried and true technology. LSP is more modern and is a common autocomplete, etc. interface for many languages.

[mwgkgk]

Just want to mention since it's not obvious from your comment, that there are both Vim and Emacs plugins to offer LSP support, and also Neovim is getting a built-in LSP implementation.