I don't really want to come across as an Atari ST fanboy in this thread (although I do love it, and the Amiga) but while TOS is very bare bones, an ST with 4MB of RAM, an HDD, and an install of Neodesk + Geneva is genuinely a nice experience.
Outside of that I've also set up a dev environment consisting of a copy of the Pure-C compiler suite (basically Borland C for the ST), MicroEMACS for editing, Okami shell[1], and pcmake[2] for a very UNIX like development environment. Most people these days would set up a cross compiler on their PC, which is the sensible thing to do, but it's been great fun to do some retro coding with on period correct hardware.
Outside of that I've also set up a dev environment consisting of a copy of the Pure-C compiler suite (basically Borland C for the ST), MicroEMACS for editing, Okami shell[1], and pcmake[2] for a very UNIX like development environment. Most people these days would set up a cross compiler on their PC, which is the sensible thing to do, but it's been great fun to do some retro coding with on period correct hardware.
[1] https://gitlab.com/wolframroesler/okami-shell [2] https://github.com/th-otto/pcmake/