What app is the best to draw on a mini iPad 5th generation using the apple pen?

"Best” is a highly subjective term.

The most popular third party drawing app for iPad is Procreate, but by no means the ONLY drawing apps for iPad and Apple Pencil.

There are MANY other third party drawing apps compatible with Apple Pencil.

Here is an incomplete list below.

Here's a long, but incomplete list of available third party Pencil drawing apps.

Sketching/Drawing/Painting Apps

Apple iOS Notes

Adobe Fresco

Adobe Illustrator

Adobe Photoshop

Affinity Photo

Affinity Designer

ArtStudio Pro ( A DIRECT competitor to Procreate )

ArtRage

ArtRage Vitae

Art Set 4

ASketch ( A free drawing app )

AutoDesk SketchBook Pro

Brushes

Brushes Redux

Charcoal

Clip Studio Paint

ColorBox Pro/Extended

Colored Pencil

Concepts

Forge

Hue paint

iArtBook/Pro

ibisPaint/ibisPaint X

Infinite Painter

Inspire Pro

Interactive Sketchbook ( purely a sketch/drawing app, no painting )

iPastels

iPocket Draw

Linea

Lori Pro

Medibang Paint

Moleskine Journal

Moleskine Flow

MyArtTools

Paper ( by We Transfer )

Procreate

Pixelmator

Pixelmator Photo

Paintstorm Studio

Realistic Paint Studio

Tayasui Sketches/Sketches Pro/Sketches School ( The School version is free, with limitations. Still a great version )

Tayasui Memopad

Water Color Pencil

ZenBrush 2

Best of Luck to You!