Something like

  1. Signal (CW, loving it)
  2. White Christmas (loved it)
  3. Love Me If You Dare (On ep 2)
  4. DROPPED- I Remember You

Something that keeps you on the edge of your seat. I'd prefer it if has little to no romance, though recommend me anything.

Oh And I checked out Liar Game, it looks really interesting, but I can't decide whether to watch the jdrama or kdrama, Any suggestions?

Thanks!

You'll love When A Snail Fall in Love, it's already in your PTW list.
For Liar game I will suggest the jdrama, It was really good!!


I also recommend:

Maou
Ryusei no Kizuna
The Quiz Show 2
N no Tame ni
Ishi no Mayu
Suisho no Kodo
Border
Tantei no Tantei
Karamazov no Kyodai
Nigeru Onna
MOZU
Lady Joker
Yakou Kanransha
Cold Case
Strawberry Night
Bad Guys, excellent crime/thriller/mystery drama (with no romance)
Personally I preferred the Korean version of Liar Game because the acting/production values were much better. I'd also recommend Pied Piper and The Devil.
Two Weeks
Limit (had some similar feeling to White Christmas)
Ryusei no Kizuna (almost no romance....but it was surprisingly funny and odd at the same time but I loved it!!)
Shinzanmono
Siren (there's some romance but the crime part is totally mind-boggling!!)
Drama Special Series Season 3: Sirius
Drama Special Series Season 1: Special Task Force MSS
Drama Special 2015: Live Shock

If you don't mind movies as well...

The Tower
Blind
Midnight FM
The Terror Live
Cold Eyes
The Man From Nowhere
 

these are some great titles listed already. I can personally second ishi no mayu, suisho no kodo, border, tantei no tantei, bad guys, & limit. I also agree with @wonhwa about preferring the korean adaptation of liar game. the jdrama is nail biting at times & matsuda shota makes it worth the watch, IMO, but I just overall prefer the kdrama.

some more dramas to add:

evil minds
yokoso wagaya e
cruel city
missing noir m

edit: boku no yabai tsuma! it slipped my mind & it shouldn't have. the first two eps are very much like gone girl but it's otherwise its own story after that, & it's great suspense.