Regenerator Golem. Nothing says a march to an AI Homeworld like 100+ Spire Frigates, a Regenerator Golem, and a few spare MKIII teleporting engineers. This was -before- the buffs granting self-regeneration, vampirism, doubled health, and halved 'build cost' (impacting repair).
After that comes the Cursed Golem, Black Widow Golem, and finally the Armored Golem.
Artillery, Botnet, and Hive golems are certainly useful (four-shot an eye anyone?), but not especially 'fun' for my style. There is just something particularily satisfying about Touhou-style bullet swarms, mass thievery, and just waltzing up to troublesome guardposts in heavily fortified AI Eye-guarded systems albeit after slipping past the fleetship frontlines. I haven't had the opportunity to try out armored since the new guard posts, though, except for one game where the initial guardian unlocks included implosion (implosion everywhere, implosion dire guardians... golems go defense). Plus that AI was a bouncer, so I got extra Implosion Guardians.