On Linux, Vim, because its ubiquitous and powerful. On Mac, BBEdit. Like the other BBEdit user in this thread, I've been using it for over 15 years, and muscle

On Linux, Vim, because its ubiquitous and powerful. On Mac, BBEdit. Like the other BBEdit user in this thread, I've been using it for over 15 years, and muscle memory counts for a lot. I also really love its side drawer for managing dozens of open files (Sublime nominally has one but it's an afterthought and not very functional), and think its symbol navigator is very effective. I especially like the ability to have the same file open in multiple windows in order to view different parts of it at the same time. And nothing else I've used quite matches its incredibly rich multi-file search/replace dialog or its search results displays (with a full listing of all instances, organized by file, navigable by keyboard, opening to the line in question in an editable buffer right in the window). And it has so many incredible text processing features. Just to name a few, a feature that will replace non-ASCII characters with their nearest ASCII equivalents; a feature to find and process (in any number of ways) duplicate lines in a file; the ability to reopen a file using a different encoding; a built in diffing tool that will work on both saved files and unsaved buffers; preserving unsaved buffers across restarts and system reboots; Markdown and HTML preview modes; a menu for scripts to run against your files/buffers; and the list goes on. Oh, and it's stable. In 15+ years of use, it's never ever crashed on me. I can't think of any other GUI program I can say that of. I've thrown 4GB files at it on a machine with only 512MB of RAM, and it somehow not only opened and rendered them nearly instantly but scrolled through them (and executed searches and search/replace) like butter.