As a fanfiction writer myself, there is nothing in the world I would recommend higher than Archive of Our Own. This site has the most beautiful writing of any other fic sites and allows you to publish any type of fanfiction that you could possibly want. However, it is hard to gain access to an account as you have to be invited and this can take 3+ days to achieve, so be patient, because it is very much worth it.
For those of you who would like to share original work with other people, my best recommendation would be Mibba, as it allows you to write either fanfiction, true stories, or original work. However, this site is extremely difficult to use, as the navigation is very confusing, and it's not known for having high quality writing.
Fanfiction.net is not one of my favorite websites but it does have one perk that I like, and that's that you can't copy and paste text from a story, which prevents people from stealing your work, so it's worth the clutter for some people. However, if you're a Phan, into Bandom or whatever, then bad luck because you can't post fics about real people on Fanfiction.net.
Personally, I've never used Quotev, but I have friends who do, and I hear that it is similar to Mibba, but easier to use. You can also make quizzes with this website which is cool!
Personally, I am very much opposed to wattpad, I think it's overrun by bad writing, but that doesn't mean it's 100% bad writing. It's very stigmatized because its infamy is widely known, so be careful if you post on this site.