Im not sure if this is true for everyones experiences. But from my experience, I swear I get WAY more rare and legendary engram drops from strike mobs than i do from patrol mobs. I am pretty sure mobs during strikes drop engrams at a higher rate despite the popular belief. Thats why I kill everything during strikes. I can run a patrol for an hour and get hardly any engrams(maybe one or two blues), but during an hour of strikes I can more than often get 8-10 blues and the occasional legendary just from the mobs. Just my 2 cents.