Its real nice to see so much appreciation for J-Jazz XD. Well allow me to pitch in some of my suggestions.
Ootaku Kaoruko: He does the Bartender OST, which is definitely worth checking out, its Bar Jazz but its very good, has a very atmospheric property to it XD
link:
(Cosmopolitan) One of the tracks
Mondo Grosso: Can't tell you guys too much about them since i have only heard a few songs of theirs but they are consistently good. They do have a more bossa nova style to them though.
Link:
(Song: Life ft Bird)
Quasimode: A friend told me about them, an i got to say they deliver such great vibes through their music, i was an instant fan.
link:
(Song: Finger Tip)
Well that's all i can think of from the top of my head, but if anyone has any good suggestions feel free to vm me, id appreciate it