And not necessarily a fantasy drama.

When I mean "high quality production" it means a lot of money has been invested in the making, and a lot of professional care has been made to make it a great drama.

A perfect example is:

Arsenal Military Academy   
Story of Yanxi Palace   
The Rise of Phoenixes   
The Story of Ming Lan   

Of course it has to be awesome as well. A lot of money doesn't mean it will automatically become great, but usually there's a correlation.

Nirvana in Fire    matches it as well, but is rather old considering how rapidly cdrama has improved.

Love like the galaxy 1       and 2

An interesting story line that unfolds at a casual pace, with a gradual development . A mix of comedy, drama with a mystery plot in political settings but most of de story line is about the family dynamics, not all on romance .

Characters are realistically written,  multi-faceted and complex.

Great actors (Zhao lu si and Leo Wu) ,  producer and screenwriter 1 (rise of the phoenix) screenwriter 2

When A Snail Fall In Love - police drama. Good characters and action scenes, reat cinematography, horrible title.

 traff:

Love like the galaxy 1       and 2

An interesting story line that unfolds at a casual pace, with a gradual development . A mix of comedy, drama with a mystery plot in political settings but most of de story line is about the family dynamics, not all on romance .

Characters are realistically written,  multi-faceted and complex.

Great actors (Zhao lu si and Leo Wu) ,  producer and screenwriter 1 (rise of the phoenix) screenwriter 2

I've seen 3 eps of love like the galaxy and it feels slow..when does the story pick up?

Princess Agents is good. 

And if you don't mind much older dramas, try The Condor Trilogy series by Louis Cha. I enjoyed The Heavenly Sword and Dragon Sabre best. 

 takarahime:

I've seen 3 eps of love like the galaxy and it feels slow..when does the story pick up?

It's not that good imo, most overrated cdrama for me. The best part about it is the fact that the emperors, his wife, and his sons are all good people. But at the same time I think the pace is too slow, it always have draggy moments where story moves slowly, and the FL is really annoyingly flawed character for me. If you watch for the actor and actress (Leo Wu and Zhao Lusi), better just watch The Long Ballad.

If you want a new costume drama you should try Royal Rumors, I like it so much more, really enjoyable to watch. FL is very strong, very intelligent, not naive.

Speaking of which, if you hate slow pace, better avoid most of those >30 ep dramas, those are often very slow and draggy, try watching dramas with <30 ep, like for example Reset has low episode count and the story moves at a fast pace and engaging.