Oh my God. These are all fantastic picks!
My suggestions:
1. Six Flying Dragons: If you're looking for a historical and you're willing to commit some time, choose Six Flying Dragons. It won't disappoint and it's one of my favourite dramas ever! It's just fabulous!
2. Just Between Lovers: If you want something heavy (some tears may follow) with a centred plot and nice camera work, go for Just Between Lovers. Great drama (but it can be emotionally taxing).
3. Because This Is My First Life: It's definitely unique and enjoyable...although I felt put off by it towards the end.
Others:
-Money Flower isn't exactly unique but Jang Hyuk plays an interesting character. It was enjoyable with makjang elements, which I love.
-Moon Lovers is like a "light" historical (but it's not exactly lighthearted) so if you want a historical that has lots of pretty things to look at and a decent story, go with Moon Lovers.
Good luck with your decision! It'll be difficult! ;)