I really enjoy reading novels to figure out the structure and rules of the power systems, but what I like even more is when there are multiple paths to power and how they interact/compete against each other. Examples are Martial World with body transformation/essence gathering/soul forging, Desolate Era with body refining/ki refining/heartforce, World of Cultivation with ling power/consciousness/mo physique, or even Warlock of the Magus World with Magi, Warlocks, Sacrificers, Beast Spirit Masters, Gods, etc. I also enjoy a novel with one system but multiple paths within the system, giving a lot of variety all the same. Examples like Coiling Dragon with the 7 Elemental Laws and 4 Edicts, Heavenly Jewel Change with all the Physical, Elemental, and even Saint attributes, or Reverend Insanity with all the different kinds of Gu Master paths (fire, ice, metal, wood, light, darkness, lightning, blood, sound, poison, time, wisdom, transformation, strength, enslavement, etc.). It really gives so much possibilities even with just one simple power system of Gu masters ranks 1-9. I also like how they handle multiple different attributes in both Spirit Realm with their Natal Palaces and also in Lord of all Realms with vortexes of attribute power. Anyway, any recommendations along these lines would be greatly appreciated. edit:Another novel that I just remember is Lord Xue Ying, which surprising introduced A LOT of new alternative cultivation systems in the recent arcs in addition to just the standards laws and profound truths system: hex, devour, ancient, voidwalker, cosmos emissary, Ancient Mother, bloodline, strongest warrior, etc. Really enjoying all the recent chapters and how it evolved from just the cliche xianxia power-up plotline.
Persuing Immortality Shen Yin Wang Zuo Supreme Uprising Long Live Summons! The Strongest Gene Monster Paradise (Perhaps?) Library of Heavens Path Soaring of Galaxia (Sorta..?) The Sacred Ruins
I liked Shen Yin Wang Zuo having different professions -warrior, mage, priest, knight, assassin, spiritist. Need to catch up on it, although I think its translation has stopped? Library of Heavens Paths had I think 27 professions? (High Nine Paths, Middle Nine Paths, Lower Nine Paths?) and also some lost professions I believe. It was locked behind a paywall before I even fell behind. Long Live Summons was about capturing spirits to battle if I remember correctly. I also remember it being very troll-y. I will look into the other novels, thank you.
Pursuing Immortality is quite good. The world essence goes up and down in a cycle, it has just recovered in modern times after hundreds of years of waning to near nothing. Cultivation methods changed over time to adjust to the changes in circumstance and changing/lost knowledge. So just within China there are different cultivation methods, e.g. MC uses Essence Consuming, Female Lead uses Thunder Manual, the government sponsored Taoist Temple uses a Neidan method as their primary because the other primary legacy among the official Taoist temples was too lost/fragmented/weak or something. They all manage to uncover some good Sword cultivation paths from a legacy site. Given it's modern times there are also other countries with different methods of their own. Europe has a bunch of wizards of varying types for example, and alchemists. There was a Celtic Druid. Japan has Onmyoji. There was a Jewish Kabbalah practitioner that explained a bit. Everyone around the world is scrambling to try and power up with the recovery of the world essence, trying to sort out fact from fiction given how much was lost. Slower start as the MC starts off with next to nothing, and isn't exactly dabbling in international politics early on. After the UN arc he also goes back to China and starts taking in disciples, so we haven't gotten to see the international cultivation systems for that long.