I'm wondering where the via location should be on the power line, considering resistance, current density and fabrication performance.
Take the following picture as an example.
Which one approach do you prefer? Any reason?
From electrical viewpoint (resistance and current density) - the answer depends on the relationship between resistivities - of metal2, metal3, and via between these layers.
As a simple example - if resistance is dominated by via (this is not unrealistic scenario), approach A is better than approach B and C.