emacs is the programmable text editor
Because of the steep learning curve and troubleshooting associated with it, I've become more hesitant in recommending Emacs. However for the curious, the video Getting Started in Org Mode [1] which is a great demonstration on Emacs and Org Mode's potential as an organizational tool. Anyone still curious and would like to smooth out the learning curve, I'd recommend using an emacs starter kit such as Doom Emacs [2] which has a lot of OOB functionality without having to immediately learn Elisp.