@john9983 More than a few have fallen into hiatus, obscurity, or otherwise can't easily be recalled by my brain, but...:
Life 4 Kaoru was sort of Team Koinaka's predecessor. They're mostly dead, but have a great backlog.
NecroManCr is a one-man team that pretty much does vanilla oneshots in an inconsistent schedule. Worth a look. Most of their stuff is catalogued on eHentai/ExHentai as well.
Scans for Humanity is a fairly recent group that's not limited to strictly vanilla, but instead to obscure/overlooked titles...of which a lot tend to be vanilla or vanilla-ish. Ditto re: eH/SadPanta archives.
Other dead groups that might be worth looking up (both here and elsewhere on the internet), though not exclusively vanilla, might be
YQII,
Sling's Translations, and
Phoenix Syndicate.