For Tapas's popular genres, I would say BL eclipses the general LGBTQ+ tag in terms of popularity. Not that the LGBTQ+ tag isn't popular, but BL on its own accounts for such a large amount of traffic, it feels incomplete with it not mentioned it on its own.
Tapas Pros: Despite the con I'm going to bring up, Tapas does offer more chances for newer, smaller stories to be featured, even if it's mostly only seen by the small community of other creators.
Tapas Cons: The readers and creators (whose stories aren't owned/licensed by Tapas's parent company) are in two different worlds. I would not be surprised if the average Tapas reader does not know that this site hosts indie comics/novels. Also the character limit can be a little annoying at times.
Royal Road Pros: Readers can review stories, which can give writers an idea of what they're doing right and wrong. It also gives other readers an idea of what to expect and can function as advertisement. You can put polls on chapters. The genres and tags are very extensive (for Royal Road's niche), and they all come with handy definitions.
Royal Road Cons: Even as someone who never plans to upload sexual content, their guidelines around it are weird, opaque, and, from what I've heard, inconsistently enforced. It's not mentioned in the site's FAQ or anything, but for a story to be allowed there, it can only contain up to 10-15% sexual content, with things like innuendo, jokes, vulgar language, etc. also counting heavily toward that. This is very strange considering some of the genres and tags they allow on their site typically have these things in spades. Feels like it would be easier just to not allow any sexual content if they're going to do this, but that's just me. There's more I could say on how weird Royal Road's moderation can be on certain issues, but for now I'm going to leave it here.
Wattpad Pros: They finally let you schedule updates. It's good for storage. In all seriousness, Wattpad's inline comments are fun.
Wattpad Cons: Maybe I am doing something wrong, but with Wattpad, you are basically posting into a void. Maybe it's better for fanfic?
Tumblr Pros: Probably one of the better sites for short fiction/micro fiction, if you're doing original stuff. Usually when I search up original writing, short, self-contained stories tend to be the most popular ones.
Tumblr Cons: Dunno how good a blogging platform is for a serialized story. Also Tumblr skews heavily in favor of fan works over original works, to the point where most writing discussions over there is assumed to be about fanfiction unless stated otherwise.