emacs

you can probably accomplish 90% of what you want without any external packages. some are very nice though. here's a few ones i use and recommend: embark consult orderless marginalia corfu cape ghelp

if (>= emacs-version "31"), emacs can install tree-sitter grammars and remap the major modes (e.g. elixir-mode -> elixir-ts-mode) itself:

(treesit-auto-install-grammar t)
(treesit-enabled-modes t)