It's very dependent on whose ratings you're getting exposed to, but here's my crack, trying to mix in some less prominent names:
Overrated: Ben Simmons, Dennis Smith Jr., Aaron Gordon, probably Draymond Green by now
Underrated: Conley Jr, Jamal Murray, Domantas Sabonis, Zach Lavine*
*yeah this is not a common pick but while his D is correctly scoffed at he's an insanely hard worker and aside from last season his efficiency as a high-volume scorer is better than people think. Kinda went the so overrated he became underrated route.