I use Reaper exclusively, all for midi, which has both good and bad sides to it.
Editing notes in piano roll is ok (there's no science to it). What I find great there is: it allowed me to setup a shortcut L for legato (which I use most of the time), predefined S to split notes, and Q to quantize, actions to change a CC lane to a particular CC (mod, pitch, expression) which I put in a toolbar.
However, zooming is strange, it almost never zooms to the content in a convenient way, so when I open an item, I often have to move and zoom around to find the notes!
CC editing definitely needs improvement. It makes me want to throw my computer out the window!
For example: when I want to edit multiple values with a mouse, sometimes it will modify only one, regardless if many are selected, so I have to undo and try again.
Or if I want to simply draw events over existing ones, and in the process click on one, it will not draw new values, but just select.
Or, if you want to use shift+drag to apply a linear transition to a range of cc values, and while doing that I happen to click on a cc event, it will again select and edit only that event, so you have to click elsewhere just to avoid clicking on any existing event (which makes me enter values I don't want, that need additional corrections).
So, essentially it gives priority to changing individual values over changing a group of values from a selection.
I also waste a lot of time drawing curves with mouse (did try scripts, but they are not user friendly).
I'm really looking forward to v6, hoping for improvements and hoping it comes out soon.
Edit: I typed the use cases from memory, they might be a bit different