I use Deviant Art as my art dump, but, well, where else I supposed to go?
Twitter is nice for promoting your art, I guess, but is absolute shit as an art gallery. It's LITERALLY the worst site I ever saw in terms of handling pictures. It absolutely wasn't designed for anything like that, it is supposed to be web's public sms shoutout, why do so many people use it that way?
Artstation is for pro art, and building portfolio for seeking job - it's a successor to the deceased CGhub.com.
Tumblr is marking everything left and right as NSFW like a rabid dog, plus it have some... interesting... crowd and reputation. Plus it compresses your artwork as well.
Furaffinity is, well, for furries, I wouldn't want to touch that with ten feet long stick.
Pixiv? Well, I guess if you draw anime you'll be right at home there. And it converts gifs into their own weird ass format.
Instagram? Isn't it that weird hipster thing where you supposed to post pictures of your food or something? It probably violates your artwork as you upload it as the rest of them, regardless.
So what's left? DA. Yes it's basically a corpse by that point, the new owners do not make anything better by introducing the so called "improved" design (that rips off ArtStation anyway), and the community is shit (or so I'm told), but it is the only popular and adequate art hosting platform that I'm aware of. It doesn't convert gifs into ugly mp4 videos, it doesn't save png as jpg, it doesn't recompress your art with bunch of jpeg artifacts, and it lets you let people download the original. Honestly the only thing that's missing is the functionality to upload multiple images per deviation.
There's always the option of just making your own site for your art with blackjack and hookers, of course, but that falls into trap of "forget anybody ever finding you on their own". Nobody will ever stumble upon your gallery accidentally or by browsing related stuff, because there is no related stuff, you are an island in the wide ocean and everybody needs a set of coordinates to just learn of your existence. So you'll need to post your stuff at the other sites still.