I’d go for 2, but also allow tags on folders.

Could a folder contain a folder? Because then maybe you could do dual posts, depending on how a sub-folder is built.

Probably no sub-folders. If anything, I think folders will just be alternative tags, sort of like tumblr's system. I want the uploading process to be as straightforward as possible, and the benefits of a complex folder structure don't seem worth it for how much it would probably clutter that.

I think 1 is the best way. But it would be useful to make it so you can assign a tag to each image, instead of just the whole post.

That's a bit like 3, then. Some combination of those 2 is what I'm leaning towards.

It would be good to have a categorization system like FA. So a user could categorize all of one character in one Category, but that category could contain a bunch of posts with multiple images i.e. comics

I personally like option 2, but I like the "old internet" approach. Number 1 is how InkBunny does it, more or less. As an artist, it's hard to say what versions you should put into one submission. If you do alternate versions but share the tags between them, you run into the problem where you have to ask yourself, "what if someone likes the first version, but a tag from the second one has been blocked?" Someone who would like version 1 and 3 but not version 2 might miss the submission entirely.

In the end, if you have this problem, you're going to just use it as though it were option 2 anyways. So, I guess it's harmless to make it that way... but I feel like a lot of people would have a good reason to not even use the feature, and you'll have wasted your time implementing it.

It's an interesting idea, but I personally don't like it.

The use case that I see more frequently on Twitter is less of an "alternate versions" one and more of a "here's everything I drew today." The utility is in making it as convenient as Twitter/Tumblr for artists to post. I know lots of artists update their FA last because you have to either click through three pages per image or use an external app to automate it. I think the only way one of these sites gains traction is if artists find it convenient enough, so that's my biggest consideration with the design.

So an answer to your question, and then a few other thoughts.

If I'm understanding right, 1 is Tumblr/Twitter style, 2 is old-school gallery site style. 3 makes no sense to me.

Neither is really better in abstract, it's a question of what kind of site you're making. "Social" sites are good for discoverability. Gallery sites are good for having easy access to everything an artist has done once you know they exist. Trying to do either on the wrong site is a nightmare. Imagine trying to find a specific image an artist did a year ago on Twitter or Tumblr. Discoverability is so bad on FA I wrote my own script for it.

I don't think you can really do both, because they're pulling at the rope from opposite ends. You could maybe do both side by side and then integrate between them, but that sounds like a nightmare for a new project just trying to get off the ground. Which means picking one, and if I had to pick, I'd go with gallery site, #2. You're not going to compete with Twitter, but you might be able to make a better FA.

But then you're entering a desert strewn with the bones of those who have gone before. Weasyl, Inkbunny, artPLZ, SheezyArt, Yerf. People have been trying to make a decent gallery site for a long, long time and it always falls apart because:

1. Websites cost money. Even more now that Cloudflare is a given cost. This is harder than people realize.
2. Websites require a carefully thought out modding policy and mods to enforce it. Lots of them. That will stay professional and work for almost nothing. This is harder than people realize.
3. Trying to host cartoon pornography puts you on constant thin ice with whoever your hosting provider is. Same with your payment processor. This is harder than people realize. Maybe even harder after Operation Choke Point.
4. First-mover advantage. Say a genie makes you a website better than FA. Right now, done, zero cost, already hosted and ready to go. There's still a good chance it fails. Because everyone's already using FA, and they're going to keep using it, despite the flaws, BECAUSE everyone's already using FA. It's like inertia, or gravity. It's a chicken and egg thing. No one wants to be the first one to move to a website no one else is using. This is much harder (to solve) than people realize.

I'd love to see a replacement to FA, and honestly believe a modest improvement/update would be fairly trivial for someone who actually cares about user experience and has their head screwed on right. But making a good product isn't the hard part. 1-4 up there are the hard part. What are your plans for those?

I plan to start hosting on GCP with Armor and see what the costs wind up being there. They permit adult content now, but if they have an issue with it I'd move to AWS/Cloudflare. For costs, I plan to use Patreon, and I have a few ideas for perks, but that comes down to marketing. If Patreon doesn't want to support me, then I'll figure something else out. I don't expect a new website will grow quickly, but worst(/best) case is I pull the plug and re-launch with ads until something sustainable could get worked out. I also have some ideas regarding scaling moderation, mostly inspired by (rap)genius. In the end, what I want is something like Twitter with a better media tab or FA with a better submission view and sharing. Hosting these websites isn't easy but if it was impossible we wouldn't be on one.

Interesting, and thanks for the reply. Sorry if that post came off harsh btw. I tend to slip into this "no-nonsense" mode when I'm really thinking something over, and forget that it might sound a little severe outside my own head.

Patreon isn't even worth trying. They have a whole briar patch of "yes but"s when it comes to adult content, and trying to accommodate their swiss-cheese policy would almost instantly make the site unusable. As you may be aware, for example, any adult content involving hypnosis is already banned there. If you were going to try a crowd-funding/donation approach, SubscribeStar is probably the only workable option, but that comes with its own issues, as it still seems a bit sketchy.

Hosting on a big corporate cloud solution like GCP or AWS sounds great, until you realize there are a lot of nasty, terrible people in and adjacent to the fandom. We're not just talking about ordinary teenager ddos attacks here. Just by trying to run a decent furry porn site, you will piss these people off, and once pissed off they will take to Twitter to form incendiary mis-information campaigns to harass Google, Amazon etc until they drop you. e621 nearly went offline years ago (Pre-Bad Dragon buyout) because one artist got pissed over how they were handling his pictures and threatened a media shitstorm over them having cub porn on the site. Careful and foreward-thinking moderation and policies help this somewhat, but you're still going to run into these people eventually.

As far as the impossibility of running/hosting a furry porn site in general, the only reason FA continues to exist is that it's grandfathered in and, again, benefits from first mover. The last furry gallery site to actually have some success was Inkbunny, which launched a decade ago. If FA had to launch for the first time now, even pre-corona virus, it probably wouldn't stand a chance. 2020 Internet is a very different world to early 00s Internet.

All that said, I'm not trying to be negative. I'd love to have a decent art site. But know what you're up against. Just trying to start an independent website is much harder than it used to be, and making that site a furry porn gallery means you have to harden it against a bunch of additional threats. If you're up for that, more power to you. I hope it comes together.

How about a sort of booru hybrid? Each image has its own set of tags, and a post can transclude any number of images as a sort of "playlist". So you can view the timeline, but you can also switch over to viewing the gallery -- and images can even be re-used in more than one post.