It depends what you want.
The killing (forbydelsen) the original danish version. think Girl with dragon tattoo, but better. Single murder case over 20 episodes. twisty, complex supsense thriller.
The bridge (broen) the original Danish version- twisty complex thriller murder cases with a contrasting pair of cops.
both major charcater are female.
Spiral- French cop show- excleent and 5 seasons so far.
The Returned- missing people keep coming back from the dead.
Da Vincis demons- fast paced reimagining of leonardo- bit fantasy- V good and fun. 3 seasons
Breaking bad 5 seasons- considered by many to be the best TV series ever. Outstanding main charcater who you believe is that person. Drugs.
Black sails- a reimagining of the pirate life 20 years before treasure island. Best pirate series ever.
Jessica jones- sispenseful marbel superhero with a difference- dark and has a lot to do with power control andabusive relationships.
24 the one that started it all-9 seasons I think.
Bayylestar galactica- best sci fi tv series- even if you dont like sci fi.
I cna add on Mad Men, Homeland, the Americans.