Which show do you think is undervalued?

For me it's Cobra Kai. Currently running on Netflix and can only say: "WOW! Really good!". Unfortunately, the series is a little under the radar.

Do you have a series where you think "Wow", but it is not watched / appreciated?

Once Upon a Time. 💚💚💚

Right, Cobra Kai is already undervalued. As mentioned here once upon a time too; i love this series!
I only think of Orphan Black (Netflix) spontaneously… I think that's really mega!

Legion only because nobody knows it F

Better Call Saul. The spinoff is even better than Breaking Bad itself, in my opinion, though it's nowhere near as well known.