Here's a list of some truly magnificent and authentic riads I've stayed at myself and highly recommend for a fantastic stay in Morocco.

A riad is a traditional Moroccan house or palace with an interior garden or courtyard. The term "riad" comes from the Arabic word "riyad," which means "garden." Riads are commonly found in the medinas (old quarters) of cities like Marrakech, Fez, and Essaouira.

Marrakech

https://tchaikana.com/
https://www.riadkbourchou.com/
https://riad-dar-sara.com/ 
https://www.riadup.com/ 
https://www.riadmehdia.com/
https://darzelda.net/

Riad Musa is next on the program, first time visit Sept 24, so I'll let you know :)

Essaouira

https://www.salutmaroc.com/
https://www.villadelo.com/
https://www.essaouira-garance.com/
https://www.lyonmogador.com/en
https://riad-de-la-mer-essaouira.ibooked.nl/
Ocean Vagabond is not a riad, but a small hotel located outside of the medina, with a pool and near the beach.

Riad Bianca is next on the program, first time visit Sept 24, so I'll let you know :)