I prefer sites that do not require membership or are free to use. This said sometimes it is worth it to unlock more pictures. the choice is yours.
booru.org/top has a list a boorus for you to explore. Gelbooru and Danbooru are two two largest.
e-hentai.org - you can browse with out a membership but with one, you can see alot more.
rule34.xxx (google: rule 34 paheal xxx to find the right one) carries many images found on the largest boorus but with some extra content. if you have very broad or unique tastes it's not a bad place to discover new artists.
Pixiv - get a membership it is THE source for alot of great art that originates from Japan. The basic membership is free and now there are alot of English tags but honestly the best tags are in Japanese. Yes, it has hentai but also is a massive source for just straight up awesome art.
Deviantart - good for a range of art. I do not typically look for hentai there but you can find erotic art work there.
sankakucomplex is good
thatpervert.com is also good and is searchable without an account.
And the "chans" you know 4chan but there are many others ....
www.allchans.org/ has a list of the most common ones.
Here's a tip: if you are on a site that has a list of the image source or a reverse-image lookup tool built in try those and you can discover other sites as well.
Another tip- search archives:
you can google what you are looking for plus:
4archives.orgyuki.laarchive.nyafuu.org/and can find a gold mine of previous threads.
Another tip: since there is so much good Japanese art, keep a file with tags that appeal to you to aid with future searches. I have a large word document with tags and their translations. This helps too to act as a back up too.
I do not know much about paid sites so maybe some one else can help you with that.
But I have heard of
https://hanime.tv/, and Fakku which may still be offering a discounted membership.
Okay, hope these help. Happy hunting.
