I only recently finally checked it out (due to an ad redirect of all things) and found myself thinking "wow I sure got lucky with that redirect"... only to eventually realize TheDoujin is THAT site linked in yellow text at the header of Gelbooru. That is some noteworthy stuff, in my book.

You'd be better off with exhentai. It's much faster for browsing and a lot more content.

Also a lot more up to date with recent releases. Not seeing any off my group's recent releases on there - or of the other groups I follow - for example.

I also like nhentai, and that's after many years of Japanese only doujin sites like buhidou or nijigazo

I don't use theDoujin, but it seems like a decent and useful site, props to gelbooru for redirecting to sites like this.

After two of my favorite doujin sites died, I switched to nhentai and I'm really satisfied with it.
But I agree with ixy that exhentai is most likely the biggest and most up-to-date doujin site out there - kinda like what nyaa was for anime/asian/hentai torrents.

The site i like to use the most is that of hitomi.la, the site is a good place for number of scanned doujinshi, including translated works there.

Many of these doujinshi posted on hitomi.la are largely reuploads from exhentai, which they import them here a lot. But since exhentai has become an typicial subscribing site, i cannot even enter that site, so i choose hitomi.la instead.

exhentai.org/

You need an "active" e-hentai account to get into exhentai. I've never done a damn thing over there yet my account works just dandy.

Sorry, i used hitomi.la, through. It needs patreon stuff to be to activate sad panda, and i don't even have patreon account. So no needed for it, i still have my hitomi.la.

No, you don't need to do anything on Patreon to enable exhentai. All you need to do is get your e-hentai login cookies moved over to exhentai. That's supposed to happen on its own if you log in to e-hentai and then just open exhentai, but you can use a cookie editor to make it happen if that fails.

Who cares about that?

Well, you seem to have a misconception that exhentai requires a subscription, which it does not, so I'm trying to correct that.