I happen to like every golem but the regen. In order of ascending awesome, excluding Mr. Botnet:
Regen: gah. Every time I find a regen instead of a different golem, I am sad. The only time I find them good is when you have two of them, teleporting engineers, and excess resources. And still, I would rather have other golems.
Armored: The armored is my second least favorite, because it doesn't really solve problems that the fleet cannot. However, when I want to glass an AI system with no casualties beyond metal and crystal, this is what I turn to.
Cursed: Long-range fleetship killer. Best simple boost to fleet power outside of a hive. And is really cheap to use.
Widow: insta-neutralizes 200 ships, and kills stuff fast. Excellent for removing those bombers from the home forcefield or grabbing a bunch of ships from a wormhole blob. I never notice the engine damage, though.
Artillery: problem structure? Gone. Duplicates of this one, however, are not nearly as useful as the first one.
Hive: If every golem were a hive golem, the AI wouldn't stand a chance. Just one of these can repel the first and second exo-wave on its own. You can use it to defend multiple planets as well, you don't have to release the full load when unloading. On offence, it is, essentially, an AIP-free nuke you can use every 16 minutes. Which also works on the AIHWs. Also is the only golem to stand a chance against an HK.