I liked both but that's probably because both Aum and Noon made those roles shine. However, personally, Mingla's character is more challenging because she goes through a lot. She goes from being a spoiled brat to a disabled person in the end. She has to marry, seduce, and sleep for survival and power, has to plot and plan to overthrow the Queen, gets pregnant, gets her babies aborted in such a torturous way, it's really tough to be comfortable enough to do those scenes and come out looking as natural as possible. Maenmuang is a good role too. She loves pra'ake but can never fully embrace him due to her guilty conscious. She has class, grace, and softness yet carries an entire country on her shoulders.
Taew is bland as a soft spoken character and then annoying as an outspoken role. Haha.