tl;dr emacs packages

Short list of good packages.
Packages listed with * are built into emacs.

company (autocomplete)
company-lsp & lsp-mode (lsp support)
*gdb (gdb debugging integration)
*dired (file manager)
evil (vim keybinds)
flycheck (syntax checking)
general (wrapper to make managing keybinds easy)
ivy/counsel/swiper (emacs internal completion)
magit (git integration)
*org-mode (powerful organizer/outliner/todo/planner/etc)
*term & eshell (terminal emulators)
*tramp (edit remote files)
use-package (wrapper to make adding packages easy)
which-key (show keybinds as you type)
yasnippets & yasnippets-snippets (insert code templates)