The Marvelous Mrs. Maisel was fabulous. They had lot of good shows in the prestige comedy or dramedy (is that still a thing?) genre. Transparent, Red Oaks, Mozart in the Jungle, Fleabag (bought from BBC)
Does Amazon really deserve credit for The Expanse? The first three seasons were SyFy, the next two were Amazon and notably less good (but still good), and then with Alex and the whole sixth season they basically took it out back and shot it for the fuck of it. I'm not saying that if they made a seventh season as a musical where the characters were furries with the effects from Cats I wouldn't still lap it up. But it feels like something Amazon bought into to milk rather than having created it.