Hi, I'm craving for sageuk lately. I haven't watched much, because I watch one at a times and so picky with the plot. Fusion or faction saeguk doesn't matter for me, as well as the number of episodes. 

So far, I already watched:

1. Arang and The Magistrate

2. Moon Embrace the Sun

3. Sungkyunkwan Scandal

4. Gaksital

5. Warrior Baek Dong Soo

6. And currently watching Scarlet Heart Ryeo and Six Flying Dragons

Please, pick me a sageuk!

If you're a fan of Melodrama, Revenge and Romance then you should definitely watch Empress Ki and The Princess' Man.
I've been planned to watch empress ki for quite a moment now. The princess man is about a time slip right? Thank you for the recommendation!
There are a few classics you have to watch if you like sageuk ^^

Priorities:
Jumong : about the founder of Goguryeo. I know you don't mind but it's 81 episodes, this shows how good it was to keep airing like that.
Queen Seon Deok : about the first woman ruller of Silla. Her ennemy, Mishil, became a reference because of how terrifying she could be. I sometimes encountered lines such as "Do you think you're Mishil or something?" in other dramas.
- Iljimae : sort of a Robin Hood. Many references as well. If you liked Warrior Baek Dong Soo, you should like it.
The Painter of the Wind : The most beautiful sageuk in my opinion. Well, it's about art so that helps. It's a gender-bender but no romance in this one.

If you need more, you can check my list.
@ BlueberryCheesecake

The Princess' Man isn't about time slip but forbidden love :)

--- The Princess' Man --- Epic romance b/w enemies, great story telling, memorable characters.. Most amazing Female lead Character!....Best, Best, Best! read the reviews.
--- Tree with Deep Roots --- excellent story about the king that created the  Korean alphabet.
--- Chuno --- Great action mixed w/ side-story of slave revolt..heartbreaking love, memorable characters, fun, sad, exciting, interesting... Memorable OST.
--- Empress Ki --- Beautiful, 1st haf is perfection!!!
--- Gu Family Book --- Fantasy, fun, rom-com w/ costumes
--- Iljimae --- Lee Jun Ki and Park Si Hoo, in a pretty good story .


Chinese Historical, since u r watching SH:Ryeo:
--- Scarlet Heart --- original C-version... concentrates more on the heroine and how she survives among Palace politics and her friendships, loves w/ the various princes... Heroine is spontaneous, carefree, but very clever and attractive, that's how she garners the interest of all the princes.
--- Sound of the Desert ---- Passionate romance, One of most amazing Male Lead characters, and the 2nd lead is pretty wonderful.


EDIT: I second @kura2ninja below, of Jewel in the Palace ... It's a classic, on my PTW,  heard lots of good things about it
I also second @nastou19 above about The Painter in the Wind .... Heard lots of good things about this
Plus, the Chinese are best at historicals: Try Nirvana in FireBattle of Changsha, and many many others.
Great recs from everyone! Let me add some good ones that haven't been mentioned:

- Jejoongwon: about a group of physicians in the late Joseon and (early Japanese occupation) era; the dynamic between the three main characters is great
- Jewel in the Palace: everyone knows this, right? It's a woman-centric sageuk about a Joseon court lady turned royal physician
- Maids: about the daughter of a noble who fell into slavery after his father was branded as traitor; I personally love the character development of the heroine

EDIT: I forgot to mention Secret Investigation Records (or Joseon X-Files). The name says it all, really. There's elements of fantasy, supernatural, natural science, philosophy and metaphysics--in just twelve episodes.
The time slip drama you are thinking of is Queen In Hyun's Man, which I can recommend btw.

Others I recommend that haven't been mentioned yet are:

Rooftop Prince
Hong Gil Dong
Sukyunkwan Scandal (Hope I spelled that right! :p)
Faith
Time Slip Dr. Jin
The Joseon Gunman
The Scholar Who Walks the Night
Mirror Of the Witch

Princess Man
Ja Myung Go
Empres Ki
What everyone above said. Yup. They're all pretty good.
You could also try Jang Ok-Jung. I enjoyed watching that and Dong Yi, which tell the same tale but from the perspective of a different concubine.

(Ja Myung Go - I dropped this around ep. 7. Anyone think it's worth picking up again?)
Ja Myung Go is on my PTW list, I've watched episode 1. The story sounds interesting - most folk tales translate well into dramas, but I'm not sure about this one.  I really wanted to watch it because I really like Park Min Young  and Jung Kyung Ho but I think Park Min Young has either been really unlucky with the dramas she's chosen or she's just got really bad judgement.  I wonder if she got lucky with Healer and City Hunter because I've dropped more of her dramas than anyone else's despite really enjoying her in the drama.  Glory Jane and Remember - War of the Son: boring cry-fests.
@IzzyDramaLovers yeah I've been considering dong yi for sometimes now, I've seen your dramalist too, thank you!

@Nastou19 I read many incredible review of Jumong, and considering it was the first drama in the order of historical timeline. So, I think I'll give it a go. I've watch Dae Jang Geum too but forgot to put it on the list. Thank you!

@Rania oops I think I got confused with Queen Inhyun man as @CherryBunny said. Anyway, thank you once again ^^

@Rainruma yeah, your recommendation was like the compilation of best sageuk ever ㅠㅅㅠ I already plan to watch most of it. And the C-drama, actually I want to re-watch pearl princess before anything. But I couldn't find any site to download it ㅠㅅㅠ and Battle of Changsa! I heard many good things about it. Thank you so much for the recommendation and the review ^^

@Kura2ninja Jejoongwon!!! I've been looking for this quite sometimes. I've heard the story but I forgot the tittle so I couldn't find it! Thank you so much! I already have Joseon X-files and ready to watch it anytime ^^ thank you!

@CherryBunny I've watched Rooftop prince and sungkyunkwan. And I dropped Scholar and faith :( But I'll try to give it a go for hong gil dong and mirror of the witch. Thank you! And by your recommendation I can tell clearly that you fancy Lee Jun Ki so much (everyone does but yeah) thank you ^^

@mighty_Brosia I've read about Jang Myung Go and I'll try to watch it! Thank you so much ^^

@Fortuna yep I've read many review about both dong yi and jang ok jung. I've read the historical backgrund too and that seems interesting. Thank you for the recommendation!

@Nat Actually healer didn't have that good rating in South Korea. I don't really like most of her drama too, but thank you for dropping by and give me your opinion!
So the ones that have stars by them are the ones that are my favorites out of them which I think you might enjoy.

empress ki *
princess' man *
the painter of the wind *
hwang jin yi *
jewel in the palace *
goddess of fire *
damo
gu family book
ja myung go
mirror of the witch
tamra, the island
queen seon deok *
jang ok jung
jin
maids
faith
king's daughter soo baek hyang *