The cinematography of both is realistic, with a documentary feel.
They are free from typical Chinese drama clichés.
Poority and rural life in focus.
They have minority Muslims, and we can see their customs.
The male characters are quite naive.

Two of them in the same time period and political situation.
My Dearest have a love story. And we can see also small fun scenes. But Fotress more about king and him ministers with sad and cold atmosphere.

Mythical-mystic things
Evil creatures
ML's brother wants to kill FL
Love story with reincarnation
Both of dramas have similar atmospheres

ML looks like a excelente husband. But he hide some things that will destroy their marriage.
FL have some relationships/friends but she didn't know they have connection with her husband secretly.
Both of them feels same in term of cinematography, music and feel 'secret'.