Pld is for encounters for when you haven't mastered as much, and war for content you have master (generally speaking).

But you have to be very lucky to collect the whole alligan set from coil, so focusing on both is a non starter for most people due to myth caps.

Pld > war though in most encounters since you can do much more with a pld then you can with a war. and 2xPld is perfectly doable, where 2xWar is a lot harder to clear contents.

War is boss though when you know the content inside out.