Geany + wolfram-geany to develop scripts that are supposed to run in the background and without REPL. Geany is very lightweight and easily extendible.
JWLS if I need a REPL, especially if I run WE on a remote server. I also use it to publish my documents/reports as html pages thanks to the markdown integration in jupyter notebooks. Usually my workflow is to write MD and do computation with the WE in a remote jupyter notebook (on my VPS) that eventually I convert to html with jupyter-nbconvert to publish it in the /var/www/html/.. folder.
P.S A new verion of JWLS is almost ready here which is even more minimalistic, more efficient and it supports Manipulate through js
