Man, that's hard to say. I have a general sense of Gnosticism as a loose grouping of diverse historical movements within early Christianity and late Paganism, but its such a vast ground to cover that I can't say what I think is most important. If I take "gnostic" as more of an attitude of approach, then I find I can relate it to Hermetic and Chaldean philosophies, which forms a useful mix.
The Hypostasis of the Archons is kind of important to me, particularly cause I can connect it to the Corpus Hermeticum's creation myth via:
“ A veil exists between the world above and the realms that are below; and shadow came into being beneath the veil; and that shadow became matter; and that shadow was projected apart. And what she (Sophia) had created became a product in the matter, like an aborted fetus. And it assumed a plastic form molded out of shadow, and became an arrogant beast resembling a lion.” It was androgynous, as I have already said, because it was from matter that it derived.
“ Opening his eyes he saw a vast quantity of matter without limit; and he became arrogant, saying, ‘It is I who am God, and there is none other apart from me.’ “ When he said this, he sinned against the entirety.
"And a voice came forth from above the realm of absolute power, saying, ‘You are mistaken, Samael, which is, ‘god of the blind.* “ And he said, ‘If any other thing exists before me, let it become visible to me!’ And immediately Sophia stretched forth her finger and introduced light into matter; and she pursued it down to the region of chaos. And she returned up [to] her light; once again darkness [...] matter."
I don't look at the Demiurge as evil or matter as error, though. I like the drama and the soteriology of the Divine Feminine. I prefer the Hermetic viewpoint that the original androgynous human spirit saw the work of the "craftsman" and wanted to emulate it. I can't draw conclusions to these mysteries, but they do inform me in deep ways,
I also like Thunder, Perfect Mind. It's heavy.
One of my projects is trying to compile a system linking the Valentinian Aeons with the Enochian Aethyrs, which I am sure has been done before. The two systems keep magnetizing themselves towards each other in my awareness.