It truly depends on whether you want to completely avoid GUI and stick to TUI and command lines. If you want to edit all of your codes within a terminal, then Vim or neovim would be the choice. Emacs can be run in a terminal, but the functionality is limited. Most people use Emacs using GUI and emacs-client not to use too much memory.
My general preference is to use an independent text editor, which is better if it is highly customizable and programmable. So, I have used Emacs for several years. For beginners, I guess Emacs requires significant time to learn to fully enjoy its wonderful functionalities. In that sense, using atom would be a recommendable option.
Regardless of all the situations, learning basic vim in the terminal will help you in any case. In summary, I recommend 1. vim as a default editor in the terminal 2. atom if you are a beginner, or 3. Emacs if you have a long-term plan to master a programmable editor
Other editors like sublime text, VS code, and so forth are also worth learning and using. But, no matter which editor you choose, stick to one or two until you become an advanced user. Being able to use most text editors at an intermediate level is waste of time.
I hope it helps.