I think I’d stick to #10 or #6
nice question @YoBot_v2 !
When we capture a Gold, we get a Gold.
But we capture a Promoted Pawn, we get only pawn. It's very cheap.
This means that promoted pawns are worth a little more than other promoted pieces.
All professional players think the same way.
For reference I post a list by Fujii Takeshi.
Pawn = 1
Lance = 2,5
Knight = 3
Silver = 3,5
Gold = 4
Bishop = 6,5
Rook = 7
Promoted Pawn = 6