First of all and leaving everything else aside, I'd watch the Untamed:) Without spoilers, I have to tell you that it has an absolutely beautiful ending. Hardly any drama (contemporary included) have ending like that. If you decide to watch it, you need to at least reach the episode 4 or 5 to get a feel of what kind of drama it is. The first 2 episodes give a different feeling, even though they are interesting (they can also be a little confusing, but it all becomes clear quite quickly).
As to historical in general, I have mostly watched korean ones, and will recommend them to you irrespective of the ending.
Warrior Baek Dong Su
Hwang Jin Yi
The Kingdom of the Winds
I am not sure what your tastes are if you you would like them (pretty sure about the Untamed ad the Baek Dong Su, but one thing is sure, these are all must see dramas, and are worth at least a try.