When would I want Rapid Firecannon over Statikk Shiv or Phantom Dancer?

Solution 1:

They all give similar stats but it's their unique perks that set them apart.

Statikk Shiv gives better wave clear and area damage in teamfights, with the lightning damage proc. Pick this one if you have a teamfighting comp or need more waveclearing power on champs such as vayne or quinn.

Phantom Dancer gives better dueling potential through the reduced damage taken from your current target. Pick this is you like to split push and often end up in 1v1 situations.

Rapid Firecannon gives longer auto attack range and bonus damage on your next attack. You can hit towers from outside their attack range with it which is why Riot says this is best for sieging. Pick this if you have a heavy objective sieging or poke comp.