EMACS and vi used to be the most popular families of text editors. There are several implementations of each.

The user interface of EMACS is mostly modeless. The user interface of vi traditionally has a command mode and an insert mode. Each character has different meanings depending on in which mode vi is in. Commands in EMACS are traditionally given by modifier keys like Ctrl, Alt and so on.

At earlier times EMACS became famous about his size and memory consumption (EMACS = Eight Megabytes And Constantly Swapping ). With todays computers this is no longer a problem.

Good Python language support is available for both editors and modern implementations such as GnuEmacs and ViImproved are extensible in Python.

Which editor suits your personal needs better is a matter of taste. Since both are OpenSource, free and mature, try both and choose one.