Autodesk Sketchbook.
It used to be an app you had to pay monthly, but it´s free now.
Sketchbook has some advantages compared to other programs.
I love the clear and easy to modify interface, everything about the app is fast and simple.
Then it has the perfect tool which is a zoom, rotate, move tool in one. You hit
the space bar and can do those 3 functions with one single tool. It makes it super convenient
when you zoom and rotate a lot. I cut out and move things around a lot and I can´t live without
this tool.
I still use photoshop, clip and other apps for other things but all the sketching happens in
autodesk sketchbook