This article is from the Amiga FAQ, by Ignaz Kellerer with numerous contributions by others.
Text Editors are programs allowing to enter and edit unformatted text. Generally, this means text that is meant to be manipulated by machine, rather than human. Programmers use these to enter the text for compilers. Since UNIX machines don't typically have word processors, most text processing starts with a text editor, then is filtered through a page layout system (TeX, for example) to produce attractive paper results.
*Commercial Products* CygnusEd Professional and TurboText seem to be the main contenders in the professional realm. The Fred Fish disks contain dozens of other shareware text editors. A demo version of TurboText is on Fish disk 445. A very old demo of CygnusEd is on Fish disk 95 (testament to its lasting-power). In the following some freely distributable editors will be discussed.
*Emacs* Gnu Emacs (the "G" is not silent) comes from Unix and is probably the king of editors - it's huge (about 1 Megabyte), feature-packed (it does windows and even contains a game!) and extensible (if you know lisp you can write new emacs functions and bind them to any key combination). On the other hand, it may be too huge, its feature-ladenness is imposing, and its extensibility often means you can't use someone else's emacs configuration. Source: Aminet (directory `util/gnu').
*Vi* The leaner, less configurable, non-extensible cousin to gnu emacs is vi (pronounced "vee eye"). Unix people like vi especially because you find it on *any* Unix machine. What you choose is personal preference, and will mark you for life. Vim is a good vi for the amiga, and is on Fish disk 591 or in the `util/gnu' directory of Aminet.
*DME* Many Amiga programmers like DME. It's fast, fully configurable; menus may be created and any key may be mapped. It's much easier to learn DME than than Emacs or Vi. There are three different versions: AmokEd, DME and XDME. It's a matter of opinion which you prefer. (Oberon and Modula programmers like AmokEd because it's written in Oberon and supports AmigaOberon error messages, C programmers like DME or XDME.) Sources: Aminet (directory `util/edit'), Fish disk 776 (XDME) and 749 (AmokEd), AMOK 90.