I'm fairly inefficient since I used to just do my LUA stuff in notepad++ before I started ren'py & python.
Right now I use Atom Text Editor with a few plugins:
- language-renpy
- custom-folds
- renpy-dialogue-plus
And the whopping 81 base packages Ren'py adds on if you let it. The reason I prefer atom is simply the layout (Multiple panes is a godsent when editing script), since indentation matters in python and ren'py, and the ability to tree any type of file etc, which makes it very organized.
Realistically, Visual Code Studio is what most people use, afaik and it's probably superior, but I'm used to Atom by now.
Other than that, ren'py itself is fairly powerful in the developer mode, since you can type script or code directly into the console and run it live, as well as giving you pretty accurate debug errors in real time, with most issues. It has LINT integration, TODO integration and a ton of useful tools to be found, even if the documentation on them is generally lackluster.
For art edits I use Clip Studio Paint, which I believe most of the team also uses (There's that one guy who uses Photoshop...)
If you're interested in VN Development there's a discord server with a lot of resources set up for it that I'd be happy to link you to, and I'd be happy to give you any input or help on discord.