What are the best freehand DRAWING apps( as opposed to painting , colour etc)?

Look at

Tayasui Sketches

Tayasui Memopad

AutoDesk SketchBook

Sketchbook

Ballpoint

Inkist

ColorBox (can be used for sketching using various color marking implements inside of the app)

Drawing App White!Board Drawing (that's the name of this app, awkward as it is)

Concepts (technically a drawing and sketching app, but its main purpose is for sketching different multiple concepts of an idea, drawing multiple product idea concepts, film/storyboarding/multiple film idea storyboarding, animation concepts, etc. Concepts is NOT strictly a straightforward "drawing app"

Here are some other good sketching apps, but haven't been updated in awhile.

Sketch Time

Graphite

Art Pencil

Also, many notes apps have drawing/sketching abilities in them, too!

Look at

Notability

NoteLedge

Good Notes

UPAD 3

and similar note apps to see if they have sketching/drawing capabilities

I have Concepts and I also have tatsui Sketches. YOu can explore those. I think they're free or have free versions