After some thinking, i landed on the general rule that if you want to go offencive, you should go for high PS and use lower PS if you plan on going defencive.
(this would work the other way as well, meaning that high ps ships should go for offence etc)
Does anyone have contradicing experiences?
The idea is that defencive ships try to wear out the enemies and should plan for taking a few hits.
(Thus, not so important to hit first, spend the points on more ships to absorb damage)
For offencive ships they rely on their damage for protection.
IE, the ships they manage to kill off will not fire back, but to do this they need to fire first.
This is probably why Rebels generally have slightly better PS than the Empire.
Most ships have no PS 1-cards but are generally high attack / low defence.
It is also why a-wings got a PS1-card - They are low attack / high defence.