OK here i m open to every category just pick one of your top dramas that u may class as first .. i know you guys may have mixed feelings about many favs but the first pops in ur head and  that made you sleepless waiting to know what s next in the next episode  is the one i m asking for .. So tell me what was that drama for you ... For example i have many that gave me that heart race and the one  that i ll mention is EMPRESS KI so plz give me one drama that is like your top of tops and u won't get bored of rewatching it all over again to see if i m missing something great ..... Thanks in advance

For me it is definitely REPLY 1997. When I tried the drama for the first time i actually dropped it because it felt so over the top and a little bit embarassing so i couldnt even finish the first episode. But my friend literally forced me to give it one more chance and... i absolutely fell in love. Like.. i usually 'binge watch' dramas moderately slowly like 4-5 episodes per day but i literally sat through whole 16 episodes because i had! to finish it! I rewatched it recently and it is still as good as I remember it so i definitely recommend it :)
The Heirs
Reply 1988
Weightlifting Fairy Kim Bok Joo
Cheese in the Trap
I'm quite new, it's only been about 6 months since I've started watching drama, but so far here is my list:

Kept me sleepless:

Heirs
Cruel Romance(til about half way through, then I got bored lol)
My Heart Twinkle Twinkle
From 5 to 9
Meteor Garden( first season only)

The ones that kept me sleepless and in my short 6 months I've had to re-watch more than once:

Empress Ki ( my favourite of all)
Cheese in the Trap
Chief Kim because it always makes me laugh or smile :)
Innocent Man 
Secret
Oh My Venus
Goblin
Descendants of the Sun
Jealousy Incarnate
For Kdramas, many of the older dramas make my heart race such as Smile You, All About Eve, Pure in Heart, Reply 1997, Vineyard Man etc...

Cdramas - definitely check out Boss and Me and Eternal Love ( 3 Lives 3 Worlds). 
Signal : time-travel police kdrama