For me, Idle Build RPG is currently the most alluring of the bunch. In fact, I've never seen so many nuanced systems, so much number crunching, in an RPG.
Loot drops are specific to the selected character, so switching classes out is key to their development. Chests can be crafted from monster drops. There are four tiers of skills, with eight freely selectable per tier. Inscriptions of verying quality can be equiped to enhance specific skills. Three attack and three defense gems, and class specific imprints can be set to a wheel to further define your builds. Relics are acquired at set levels and grant passive skills and abilities.
Mercenaries can be used upon reaching level fifty, and can choose from forty skills taken from the main classes. At level one hundred, each class can choose from two Job changes, for instance, the Knight can become a Heavy Cavalry, or a Paladin. At level one thousand, two more job changes are available, The Knight can choose from Dragon Rider, or Black Knight. And there are even more job changes further down the line.
It should be noted that increased options appear into the long game. Accent on 'long.' Artifacts, peak points and the like. Upon reaching a base level of one hundred, one begins acquiring 'peak levels' which at certain milestones further broaden an already burgeoning build palette.
Some upgrades evolve naturally, and some can be upgraded with in-game currency. Boosts to XP, power, and currency can be purchased, last a limited time, but do stack. Note, all currency is earned in-game.
The game keeps track of statistics for all classes, along with a general stat tab.
Basic game loop consists of entering a map location, and attempting to reach it's highest levels, while opening more locations on the world map.
As you might expect, this is an enormous time sink, which from your perspective could be good or bad, considering the asking price, I think it's a net good.
One typical caveat about these Okyakusama games, there is no sound other than the click of your pointer, and no music whatsoever. You get used to it. If you play windowed, you can listen to your favorite content creator at the same time.
A surprisingly robust entry into the genre!