I post here on Tapas, Royal Road, and Wattpad.
RoyalRoad thrives on LitRPG. LitRPGs are stories where JRPG-based systems are front-and-center. Things like levelling up via experience points, character builds, dungeons, anything where numbers are climbing up. Progression fantasy is also popular there. From what I gathered, it's basically any fantasy where the main character gets noticeably stronger over time. I've heard of sci-fi and cyberpunk books doing well there, but anything that isn't LitRPG has a bit of an uphill battle in store.
Heavy romance is kind of frowned on, but GL is generally received well there. And as long as you tag your story with the appropriate warning, most violent content should be fine. Sexual content is the big no-no on that site.
Royal Road has, in my opinion, the best UI out of any writing site I've seen so far. It has limited genre tags similar to Tapas, but there's a wider variety of them. There's also limited subgenre tags, with even more options to choose from, though there's no dedicated GL tag (for admittedly weird reasons.) You can preschedule chapters. Royal Road has a pretty in-depth search system, and there's a way to see newest releases. If you want to grow an audience there fast, it's best to build up a backlog and release daily to take advantage of the new release section. Even if you're writing in a less popular genre, it's easiest to get seen there from my experience.
I've only seen scribblehub once or twice. Most of my knowledge of it is based on what people from Royal Road have to say, so take it with a grain of salt. Scribblehub has kind of the same demographics as RR in terms of what's popular there, but way more smutty in an anime kind of way.