Re: c) I will be a dirty shill for VSCode and R lol, example here. I find it much better for R shiny development, projects with multiple people and projects with multiple languages. Notebook support is less good out of the box, you will have to get a jupyter kernel set up - but I use scripts more so than notebooks anyway.
Anyway, onto the question! Base R. Yeah, I said it! Whenever I have a weird enough situation where tidyverse functions won't work due to poor quality data, then I shed a single solemn tear and quietly wish I had done the project in python as I start writing a for loop in what will no doubt be the most hacky solution ever.
That no one knows it. For many ML algorithms they rather get published first in R than in Python still, although I believe this is not true for deep learning, but rather stuff like tree based models.
Sometimes I can’t implement what I want to because I don’t have time, let alone skill to port a library from R into Python and make it sklearn compatible. But I also don’t want to be the only person in my team who understands the code. So Python it is.
Edit: just realized this is 7 months old, but I guess maybe we can boost activity by also answering to old posts?