lol
there are 2 types of marauders possible
- housing aggressor
- agriculture aggressor
I prefer the first anytime because it`s always fun to steal as many planets as you can, populate them AND get paid very good for plundering :D
the second one is an option IF the foodprices are high, if not it`s not worth it in my opinion,
some also combo them but I think that`s just a waiste of research lvl`s, do them all in housing and you get paid the best