Generally speaking, I reserve hacking for ARS first (though it scales up dramatically), super terminals second, and knowledge hacks third.
I'm currently playing with Fallen Spire, Spire Civilians, Showdown Devices, and as high AIP as I can manage on a spiral map, along with vengeance generators and other Fun Stuff. I'm struggling with it a bit, but as of hour ten I think I've broken past my roadblock at around 300 AIP.
I'm very likely to take a system for the knowledge along the way, so the only reason I would knowledge hack would be if I was 250-1000K short of a key tech. For instance, if I had Spirecraft off, I can think of one situation where I would most likely need Mark IV Bombers and Mark II/III Cloaker Starships. I was able to squeak my way past with rams and a cloaker starship. If I had Fallen Spire off, I wouldn't have been so obsessed about setting up a chokepoint, despite the adjacent Dire Guardian Lair. If I had Spire Civilians off, I'd have at least 100 less zero-calorie AIP, but no reoccuring reduction.