Hello, I use a number of tools, each with their positives and negatives. Among them OneNote, Notability, & Omnifocus.
For the above two, it is easy move what are called categories in agenda, with a mouse to organise things how I want (the alphabetic option is useful but not enough). This would be a very helpful addition.
Next is nesting, I have seen posts on this so am not alone.
It would be good, at a minimum to be able to nest projects (far left window). Nesting categories would be useful as well. Nesting ideally would have expand and minimise options.
This will speed navigation in the main screen.
Having these features would knock out one or more tools that I am currently using.