I tend to agree about the "padding", though it's the constant romantic interludes that bore me.

Bad Guys

Who are You

Angry Mom

Heartless City

Two Weeks

Liar Game

Kill me, Heal Me. 

The Guardians.

Flower Boy Next Door.

It's Okay, That's Love.

Shopping King Louie (really soft, for me it was like a feel-good drama kk)

Master's Sun.

You Who Came from the Stars

And, so far, for me That Man Oh Soo too, its still airing but I finished 12 episodes in a single day 

Definitely Healer (each episodes builds up to a more exciting episodes especially the love lines)

Also for me:

Money Flower (consistent)

Master's Sun 

Empress Ki (my POV is that each episodes is unique, the character development especially for the king is impressive, dont mind the 51 episodes, they are all worth your time to watch)

Because it's my first life

Sungkyunkwan Scandal (all eps are enjoyable to watch, no boring eps)

Defendant (all eps are executed well)

Oh I forgot to mention

Seven Day Queen

Scarlet Heart Chinese

Pride (Japanese) - really good, till the end

One other Korean older one I'd recommend is Lucifer (2007) Uhm Tae Woong, Shin Min Ah and Joo Ji Hoon. There was a Japanese re-make with Ikuta Toma (Maou). Both are watchable, in some ways the Korean one is better.

Marriage not dating 

So many good recommendations, so little time………….

 ShotaSidePart:
If they cut all the flashbacks out of it the show would have been 8 episodes -_-

Hahaha, true that

Bad Guys

Circle

Moon Embracing the Sun

Drinking Solo

38 Task Force

Goblin

Save Me

Just Between Lovers

Cruel City

You Who Came From Another Star

King2Hearts

Reply 1997

Another Miss Oh

Kill Me Heal Me

Another Miss Oh

A Gentleman's Dignity

Gaksital

Gu Family Book

Some were already mentioned but these are my recommendations: 

1. Birth of a Beauty ---->  revenge & romance go hand in hand with this one. Keeps you on the edge of your seat and you get comedy, romance and revenge all in one.  I was never bored with this one. 

2. Jugglers ---> office drama meets romance. Her boss really hates her in the beginning which only makes the romance better as he falls in love with her and it's never boring because although there is romance happening, the drama that comes from other characters and the company itself is what makes this power couple one of my favourite on-screen couples. 

3. Master's Sun ---> I was quite skeptical about this because I didn't know how any plot would really turn out but boy was i wrong.  Not only did it have me hooked, the romance practically made me giddy the whole time and the side drama is what really pivots the drama forward. 

Hope it helped! 

Ugly Alert

The Master's Sun

The Greatest Love

Gaksital

Stranger

Healer

Scent of a Woman

Queen In Hyun's Man

Nirvana in Fire (Chinese)

Bu Bu Jing Xin (Scarlet Heart) (Chinese)

I couldn't in good conscience leave off the last two even if this is the Korean drama thread. XD There are a few more dramas I'd add if I allowed myself to recommend dramas based purely on my emotional enjoyment and not on whether it's objectively good. haha 

I just finished “ Mother’’ yesterday.  The feels from the start to the end. The first episode left me shook literally. 

Just finished Secret and I gotta say- not bad, not bad at all. It came recommended and I'm glad I watched it.