Both have honorable, kickass protagonists fighting for their idea of a better world. Both have moody settings, a lot of action and suspense, and plenty of plot twists and political schemes.

This might be a bit of an unusual suggestion, but if you loved the mature and self sacrificing Crown Prince Yi Jin and/or Officer Min Woo Won in Rookie Historian, and I think you'll really like the Crown Prince Lee Chang in the Kingdom series.