Arslan Senki, Guin Saga Recommendations
They are both based on epic fantasy novel series with historical elements, rise and fall of kingdoms, magic, politics, wars, heroics; both stories are influenced more by Persian epics rather than Japanese or Asian influences
The source materials for both are long novels series, yet both are also similar in the sense that their anime counterparts are incomplete. However, each of them definitely capture the essence of their expansive fictional worlds modelled after historical periods and places, and the grand scale of the storylines.
The intricacy of the plot, albeit unexplored due to the lack of completion, and the diverse cast of characters also carry a similar vibe. Political intrigue and different 'sects' of characters are prevalent in both. And they contain fantastical elements, though more so in Guin Saga than Arslan Senki.
And both series have rather melodious ending themes.