If you go by quantity of areas within a god’s purview, then two-faced Janus, god of doorways and thresholds, and Baron Samedi of the crossroads are definitely up there, with Janus having a slight edge, although Samedi is reputedly a lot more fun at parties. St. Daedalus, patron of labyrinths, is well-nigh universal, but not many people pray to him, for much the same reason that people often don’t pray to rain gods when they’re hip deep in floodwater.
In terms of active, present gods, Anubis, that tall and kindly darkness, is probably the top. People get lost a lot in the Gearworld, and sometimes they need a guide. (Sometimes they don’t. Sometimes they do and don’t know it, and occasionally, they get one whether they know it or not.) The infinite compassion of Ganesh extends down here, and his shrines are some of the pleasanter areas of Gearworld, rather less prone to suddenly reorganized reality than elsewhere. And there’s a lot of local gods, too, incidental gods, all-powerful within a few corridors—the Silkenrude and Our Lady of Grackles, the random and cryptic angels that appear, smiling blindly, inside the walls. And all those people in hooded motley probably worship somebody, but they don’t talk about it (and let’s face it, for people that dress like slightly deranged jesters, a surprising number of ‘em have absolutely no sense of humor. Actually, maybe it’s not that surprising. Jesters just aren’t very funny.)
But in terms of raw numbers of followers, the top god, by leaps and bounds, is one of the least—the God of Small Things. Very small things worship him, almost without exception. Mice worship him. Rats have their own complex, tightly stratified hierarchy of deities, of course, but they still acknowledge him, in much the same way that Catholics can have a terribly complex system of saints and still pray to the Virgin Mary. (Who also has a few shrines down here, somewhere or other.) Similiarly, while slugs and snails of religious mien mostly worship the great Starslug, plenty of them also acknowledge the God of Small Things. Dustbunnies worship him, (yes, there are dustbunnies in the Gearworld) and their strange folk hero, the Peacock, is supposed to be a close confidant of the God of Small Things. Preying mantises do not worship him, being atheists to a bug, (the prayer thing is an evolutionary coincidence, no more) and social insects all follow their respective imperial cults, so he isn’t well represented among the insect orders, most of which are non-sentient anyhow. He does a brisk trade in the prayers of goldfish, however, and voodoo dolls have been known to convert. All the small, the meek, the tiny and insignificant are welcome to his shrines.
Many gods within the gearworld are shown wearing hoods or blindfolds, the notion being that they do not need physical eyes to see. This has been picked up in the clothing of some groups, including those hooded motley guys, and you can generally pick out who’s cool among such groups by watching who actually runs into walls and who doesn’t.
I have no idea, but it wanted to be written down. The phrase "the God of Small Things" has rattled through my head for years on end, and I'd love to paint a small shrine to him, but I don't know what he looks like yet. I tried a sketch but it just wasn't the right god...I have a feeling it's gonna wind up looking a lot like the Laughing Buddha, but with some key differences. Except that I don't know what those are yet.