These three things are much needed
Auto Detection of Arrows is very helpful in many cases
Dotted Lines/Dashed Lines are very necessary in Making Diagrams especially in mathematics and physics
Duplicate feels more easy than copy and pasting the thing, adding duplicate with copy will save time
Inverting PDF too seems necessary sometimes

Only because of these 4 functions I have to sometime switch to notability and it does not feel good cause I have paid for GoodNotes